The 26-year-old defender has agreed a contract at Stamford Bridge until 2032 following two successful years with the Eagles in which he made 98 appearances and won the Conference League, FA Cup and Community Shield.
His performances earned him a place in France's World Cup squad, where he made three appearances as Les Blues finished fourth.
"I am really happy to be part of this beautiful club," Lacroix told club media.
"Everyone knows the legend of Chelsea, its tradition of winning, and to be a part of that is a proud moment."
Lacroix becomes Chelsea's third signing of the summer transfer window, joining Morgan Rogers and Marco Palestra in moving to west London, as the club prepares for its first season under Xabi Alonso.
It was a chat with Alonso that helped the former Wolfsburg man with his decision to move.
"When I spoke with the manager, I saw that we have the same direction and desire for this club," he added.
"We want to win. When you see the quality of the players here, everything we have around the club, it's something that we can achieve.
"The ambition is to lift trophies, and I can't wait to contribute."
Lacroix signing 'offers a glimpse into Chelsea's future direction'published at 11:23 BST
11:23 BST
Nizaar Kinsella Chelsea reporter
Image source, Getty Images
Mexence Lacroix had been on a shortlist of centre-back options since it became clear Chelsea's defence was underperforming and that they needed more physicality and leadership in their back line.
Although former Manchester City defender John Stones and Como 1907's Jacobo Ramon were also known to be under consideration, it always felt as though the 6ft 4in defender was Chelsea's preferred target.
Protracted negotiations over both personal terms and the transfer fee with Crystal Palace added uncertainty to the deal.
However, Lacroix gave the move the green light last week after France's World Cup campaign ended with a fourth-place finish following defeat by England in the bronze-medal match.
The signing also offers a glimpse into Chelsea's future direction after a season in which they finished 10th in the Premier League and ended the campaign without a trophy, prompting frustration among supporters.
Owner Behdad Eghbali said Chelsea would "tweak" their model and add experience to what he still believes is a strong core of young players, including Cole Palmer, Moises Caicedo and Levi Colwill.
These are all deals that are highly unusual for the club's recruitment strategy.
The Blues also attempted to sign Granit Xhaka, 34, from Sunderland earlier in the summer so are sending a clear message that the club's approach is changing.
Along with £117m signing from Aston Villa, Rogers, who turned 24 on Saturday, Lacroix's arrival means Chelsea have delivered on their pledge to make at least two ready-made signings.
Welbeck will become the oldest signing under the Todd Boehly and Clearlake Capital ownership, until Henderson's likely arrival with the west Londoners.
After interest in Sunderland's Granit Xhaka did not materialise into a deal, attention pivoted to other targets as part of new manager Xabi Alonso's drive to add experience to Chelsea's squad, which has been the youngest in the Premier League for the past two seasons.
But aside from a wealth of trophy-winning experience, Henderson also brings with him something brutally exposed as lacking from the Blues' squad - legs.
No player to feature five or more times in the Premier League for Chelsea last term covered more ground per 90 than Henderson's average of 11.86km. Despite being 36-years-old, he started 22 times and was bought on a further 10 times.
Already since his arrival, Alonso has stressed the importance of energy and intensity. Speaking on the Blues' pre-season tour, he said: "We need good energy. We need to run. We need to work hard. We need the sacrifices which are compulsory and mandatory in each Premier League game. To win each game, it's tough. We need to prepare for that."
Last season, remarkably, the first time Chelsea outran an opponent was against Liverpool in their 35th match of the campaign. It is unlikely Alonso will allow a similar pattern to develop.
The Spaniard is known for his willingness to participate and be hands-on in training sessions and told club media, before Chelsea opened their pre-season with a win over Western Sydney Wanderers, that: "I need to be close to the team, to participate with the energy, with the intensity I like."
Alonso cannot marshal the Blues' midfield himself, so a big character to be his voice on the pitch and lead by example with intensity and energy - as Xhaka did for him during his time at Bayer Leverkusen - is imperative to maintain standards.
Enter Henderson, with his impressive running stats and track record as a leader.
Eyebrows were raised by his inclusion in England's World Cup squad this summer, but Thomas Tuchel insisted Henderson is "the glue in every team that he plays for" and new Chelsea team-mate Morgan Rogers said he is the "best guy I've ever come across in football".
Speaking two years ago on former England goalkeeper Ben Foster's podcast about a game in which their Watford side was comfortably beaten by a Liverpool team captained by Henderson, Tom Cleverley said: "He was like an on-field manager with so much quality to go with it. Even players like [Mohamed] Salah and [Sadio] Mane were looking at him like, 'help us'. They completely respected Henderson and knew he was their leader. They would have followed him anywhere."
Three glaring issues in last season's Chelsea squad were inexperience, a lack of leadership, and a repeated inability to match an opponent's energy and running.
In pursuing Henderson, the Chelsea board have identified these and are looking to address all three. In this sense, it is a move that makes a lot of sense.
Who is Dastan Satpaev?published at 08:58 BST 29 July
08:58 BST 29 July
Nizaar Kinsella Chelsea reporter
Image source, Getty Images
Dastan Satpaev is attempting to become the first Kazakh player to appear in a Premier League match.
In his homeland, he is a superstar. He has already played for his national team and attracted fans from his home country to both the open training session on Sunday and the match on Tuesday in Sydney.
Quick, sharp in the box and relatively small in stature, Satpaev is stylistically often compared to former Argentina and Manchester City striker Sergio Aguero.
Asked whether he will get a chance at Chelsea this season amid talk of a potential loan move, Xabi Alonso said: "We still have to take decisions.
"I knew Dastan from Almaty," added Alonso, who faced the player with his former club Real Madrid last season.
"He is a ball threat, he attacks the inner channel well and is good as a striker coming from the outside.
"He is really strong, really quick and I have been really impressed with him."
Referees call for VAR tweakpublished at 07:23 BST 29 July
07:23 BST 29 July
Image source, Getty Images
Video assistant referees should only be used to change "blatantly incorrect" decisions and clear missed incidents, say European refereeing officials.
Chief refereeing officers from all 55 European national football associations met last week with Uefa refereeing officials and a representative from the International Football Association Board (Ifab) to address recent changes to the game's laws.
Attendees said "lengthy, microscoping reviews" indicate VAR has gone beyond its original scope.
When VAR was added to the laws of the game in 2018 by football's rulemakers Ifab, its "philosophy" was "minimum interference - maximum benefit", with the intention of reducing "unfairness caused by clear and obvious errors or serious missed incidents" relating to goals, penalties, direct red cards and mistaken identity.
Uefa said that at its recent meeting that refereeing bosses agreed a return to those original aims is needed.
"It was reiterated that, in accordance with protocol, VAR must only intervene in situations of 'clear and obvious' error, ie. when a referee decision is blatantly incorrect or when the referee has missed a clear incident," Uefa said in a statement.
"VAR is not meant to re-referee the game, it is an essential support to the referees, who must remain at the centre of all decision-making.
"Lengthy, microscoping reviews are often a symptom revealing that the decision on the field was not clearly and obviously incorrect, and should therefore be limited."
What we learned about Alonso's planpublished at 16:57 BST 28 July
16:57 BST 28 July
Nizaar Kinsella Chelsea reporter
Image source, Getty Images
Xabi Alonso, who was a vocal presence on the touchline during Chelsea's 6-4 win over Western Sydney Wanderers on Tuesday, used the 4-2-3-1 system favoured by former Blues boss Enzo Maresca.
With players still on holiday after the World Cup - including club record £117m signing Morgan Rogers - several youngsters were given an opportunity.
Midfield trio Mahdi Nicoll-Jazuli, Reggie Walsh and Reggie Watson all impressed, with the latter the only player to play the full game.
Nicoll-Jazuli and Watson, both 16, anchored the midfield together for long periods, while 17-year-old Walsh operated well in a more advanced role.
In his pre-match news conference, Alonso expressed surprise at how well the seven academy players drafted in to fill gaps in the squad had performed in training.
Landon Emenalo, 18, has also been given a significant opportunity, with no other left-backs available.
The only senior player other then Joao Pedro to particularly impress was winger Jamie Gittens, who made it three goals in three appearances in pre-season, following his two in behind-closed-doors friendlies against EFL opposition.
Are Alonso's Chelsea prioritising experience over youth?published at 16:26 BST 28 July
16:26 BST 28 July
Simon Casson BBC Sport senior journalist
Image source, Getty Images
Chelsea are targeting deals for Maxence Lacroix, Danny Welbeck and Jordan Henderson and the ages of the experienced trio, especially the latter two, seem to signal a major change in transfer tactics from the Blues.
At 26 years old, it could be said that Crystal Palace defender Lacroix is in his prime, but the £52m target is still notably older than other recent Blues signings.
It has been two years since Chelsea signed a player older than Lacroix, and Tosin Adarabioyo was only marginally older when he arrived three months before turning 27.
Welbeck's potential arrival could mean a 35-year-old replacing 23-year-old Liam Delap in the first-team picture, despite the former Ipswich Town man being considered one of the Premier League's most exciting young strikers when Chelsea signed him last year.
So does this signal a deliberate change in recruitment strategy, such as prioritising experience over youth? And what might Chelsea have learned from recent seasons?
Well, if his previous managerial approach is anything to go by, Xabi Alonso favours a blend of youth and experience.
The Spaniard signed four players over the age of 27 for the 2023-24 season at Bayer Leverkusen- including Granit Xhaka and Alejandro Grimaldo, who became key players in the Bundesliga title-winning side.
Another four players over the age of 27 came in the following season - and it could be a similar story now at Chelsea.
'Improve quickly' - Alonso's assessment of opening matchpublished at 14:19 BST 28 July
14:19 BST 28 July
Nizaar Kinsella Chelsea reporter
Image source, Getty Images
New Chelsea manager Xabi Alonso says he wants his squad to "improve quickly" after a chaotic 6-4 win over Western Sydney Wanderers in his first match.
The Spaniard, 44, made his comments in the context of being asked about the talks to sign experienced duo Danny Welbeck, 35, from Brighton and Jordan Henderson, 36, from Brentford.
On his Chelsea bow, Alonso oversaw a side that showed the quality to score six times but also offered a side of their display that boasted ample errors.
When asked whether experience would improve Chelsea in light of the performance, Alonso replied: "Everyone has to learn, everyone.
"It doesn't matter if you are young or more experienced. This is what happens in the game and this is a quality you need as well.
"You can be quick, you can be good at dribbling, but you also need the game intelligence to do the right things. In every aspect we need to improve quickly because the competition starts in almost a month and we want to be ready for that.
"We need to manage that. It is so important in football nowadays."
Alonso's comment was also linked to the impressive pace in which Chelsea have acted in the transfer market but with a need to potentially do even more.
They secured deals for £117m forward Morgan Rogers from Aston Villa and Crystal Palace defender Maxence Lacroix, along with the acquisition of Atalanta full-back Marco Palestra, who made his first appearance at the Accor Stadium.
Alonso's assessment followed a performance that featured "positives" but also highlighted poor "game management" and an inability to find "solutions" to the Wanderers' tactics.
There was also praise for substitute Joao Pedro, who scored a 10-minute hat-trick and was described as "very hungry", while Alonso revealed Romeo Lavia did not feature because there was "no point in taking risks" after he "felt something in his hamstring".
Joao Pedro treble helps Alonso to first winpublished at 12:59 BST 28 July
12:59 BST 28 July
Image source, PA Media
Xabi Alonso's first game in the Chelsea dugout ended in a 6-4 victory over Western Sydney Wanderers in the pre-season Sydney Super Cup competition.
Joao Pedro proved his quality when coming on from the bench - the Brazilian forward scored a hat-trick and assisted Jamie Gittens' goal in the space of 26 minutes.
Chelsea trialist Dastan Satpaev and midfielder Dario Essugo also scored, but defensive frailties throughout the match cost the Blues four goals.
Alonso named a youthful starting XI and used all his substitutes, except for Ted Curd, Calvin Diakite and Romeo Lavia.
Chelsea will face Tottenham next at the Accor Stadium, Sydney on 1 August (10:45 BST kick-off).
Select player ratings by Chelsea reporter Nizaar Kinsella:
Joao Pedro: The Brazilian striker scored a hat-trick and simply outclassed and overpowered lesser opposition during a sensational, match-winning 30-minute cameo. Maybe he was angry having been left out of Brazil's World Cup squad. 9
Jamie Gittens: Equalised for Chelsea after initially hitting the target with a good shot as part of a great early impact. It's three goals in three games for Gittens, including two in two behind-closed-doors before today, during this pre-season. He is looking sharp. 8
Dastan Satpaev: The Kazakhstan forward became the first goalscorer of the Alonso era despite not yet officially being a Chelsea player. The 17-year-old will join permanently when he turns 18 in August and made an impact before completing his move from FC Kairat. He burst away from German Ferreyra before firing in a near-post finish to open the scoring in the sixth minute. Although he blazed over in the 31st minute, he was again involved in Chelsea's second goal. 7
Reggie Watson: Watson looked tidy in possession but also gave the ball away on a couple of occasions. It was impressive that the 16-year-old, the youngest player in the squad, was selected in the first place and he hit a powerful second half free-kick just over. He was the only player to complete the full match. 7
Nicoll-Jazuli's physical presence belies his agepublished at 10:59 BST 28 July
10:59 BST 28 July
Nizaar Kinsella Chelsea reporter
Image source, Getty Images
Seven academy players have been taken on Chelsea's pre-season tour - and they will all be looking to impress new boss Xabi Alonso.
The Blues are travelling to Australia with a 26-man squad, and are facing Western Sydney Wanderers and Tottenham.
Almost all of the academy players have been training with the first team throughout Alonso's first two weeks in charge, featuring in behind-closed-doors friendly wins against Crawley Town and Bromley.
However, they could return to London during the Asian leg of the tour if the players involved at the World Cup rejoin the squad.
Mahdi Nicoll-Jazuli is one of the young players hoping to make an impact and break into a star-studded - perhaps oversized - Chelsea squad.
Nicoll-Jazuli became the youngest starter and goalscorer in the Uefa Youth League last season and has consistently played above his age group thanks to his outstanding athleticism.
He is developing into a high-energy, technically gifted midfielder in the mould of Cobham graduate Mason Mount.
His involvement on the tour represents something of a homecoming. His mother is Australian and he is eligible to represent Australia, France and England at international level. He currently plays for England at youth level.
Alonso said: "I'm really impressed with him. Mahdi is one of the talents we need to develop, as he has special qualities that you don't often see in a 16 year old.
"He is a dynamic player. He can pass short and dribble in the middle. He has made a good impression so far."
Chelsea are delighted to have secured Nicoll-Jazuli's long-term future, after facing competition from leading French sides, with a new contract set to be signed when he turns 17 in January.
'Experience and camaraderie' but Blues need more than 'motivational speakers'published at 09:21 BST 28 July
09:21 BST 28 July
Image source, Getty Images
We asked for your views on the wisdom of Chelsea moving for 35-year-old Danny Welbeck and 36-year-old Jordan Henderson.
Here are some of your comments:
Will: Welbeck and Henderson would provide the much-needed experience we lack in the squad. John Stones would be a better signing than Henderson - however, Welbeck can also provide a goalscoring threat.
Steve: Welbeck is a good pro and would be a good addition to the squad. Henderson - no.
Scott: As far as dressing-room experience and camaraderie goes, these are good moves. However, I doubt Henderson and Welbeck will take us to the next level on the field. This would also only highlight how much of a shambles our transfer policy has been.
Cris: It's a good thing to get players with experience but not players who are past it. Chelsea still need a good number nine with experience.
Julian: It would be good to sign Welbeck and Henderson. They have got a lot of Premier League experience and would help to see out games, which was something we could not do last season. And their experience around the club would help the young players.
Jack: I like the Wellbeck move in theory, particularly if it means we can say goodbye to Liam Delap. Henderson feels like a great voice and leader to have onside, but I worry about his ability to deliver any kind of cup winning performance. We need players not motivational speakers.
English football set for key goalkeeper trialpublished at 06:59 BST 28 July
06:59 BST 28 July
Image source, Getty Images
English football is set to implement a trial to try to eradicate the goalkeeper tactical timeout this season, BBC Sport can reveal.
The Football Association, Premier League, English Football League, National League and Women's Super League have agreed on the measure, pending permission from the International Football Association Board (Ifab).
Earlier this year, Ifab decided against changing the law and invited leagues to volunteer for trials.
Pro Ref, led by chief refereeing officer Howard Webb, has been in discussions with the leagues to determine how to tackle the issue. It settled on a team having to remove an outfield player from the field.
If a referee signals that the physio can come on to treat a goalkeeper, the coach will have 10 seconds to nominate another player to leave the pitch for one minute, telling the fourth official of their choice.
If no player has been selected within 10 seconds, the captain must leave the field.
Why Chelsea's Welbeck move is astutepublished at 22:33 BST 27 July
22:33 BST 27 July
It says everything about Danny Welbeck that senior figures at Brighton were convinced England should have taken the veteran striker to the World Cup as a back-up.
Forget about his age. Welbeck featured in 37 out of Brighton's 38 Premier League games last season. His 13 goals put him joint-ninth in the list of top scorers, with only three Englishmen bettering that tally.
Those statistics show him to still be a top forward.
Then there is his overall game - his ability to hold the ball up, bring team-mates into play or buy his defence some valuable time.
Finally, there is Welbeck's presence behind the scenes. He is someone who drives standards, makes demands of team-mates; someone for younger players - of which Chelsea have plenty - to learn from.
Manchester United tried to bring him back to Old Trafford in the past but it did not quite work out. Welbeck is the kind of forward they need now.
But it is Chelsea who have acted first. One of the most surprising deals of the summer could turn out to be one of the most astute.
Welbeck and Henderson - what are your views?published at 19:38 BST 27 July
19:38 BST 27 July
Image source, Getty Images
Many fans called for Chelsea to introduce experience into the club's ranks and it seems the hierarchy at Stamford Bridge have been listening.
In the summer where the Blues moved for Granit Xhaka, they are now in talks to sign both Danny Welbeck from Brighton and Jordan Henderson from Brentford.
So, is pursuing the pair - Welbeck is 35 and Henderson 36 - a wise move or are the Blues going from one extreme to another? Is there a better balance to be struck? Or do you think these older heads will offer plenty?
Image source, Getty Images
