Thiago Silva has completed a move to Chelsea on a one-year deal after passing a medical on Thursday.
Chelsea have the option to extend the contract by a further year for the Brazil centre-back, who became a free agent following PSG's Champions League final defeat to Bayern Munich.
The Ligue 1 club confirmed the 35-year-old's exit on Thursday – despite last-ditch efforts by the Champions League runners-up to offer him a new deal.
Silva, who spent eight years with PSG after joining from AC Milan in 2012, is Frank Lampard's sixth signing of the summer following the arrivals of Hakim Ziyech, Timo Werner, Ben Chilwell, Malang Sarr and Xavier Mbuyamba.
"I am so happy to be joining Chelsea," Silva said.
"I am delighted to be a part of Frank Lampard's exciting squad for next season and I'm here to challenge for honours.
"See you soon Chelsea fans, I look forward to playing at Stamford Bridge very soon."
With Chelsea keen to strengthen having been banned from signing players last summer, the London club could also complete a deal for Bayer Leverkusen forward Kai Havertz before the start of the new season.
Silva won seven Ligue 1 titles during his time in France, but leaves the club having failed to achieve the European success desired most in Paris.
Despite sealing a fourth-placed finish and qualification for next season's Champions League, Chelsea struggled defensively throughout Lampard's debut campaign in charge at Stamford Bridge.
Chelsea director Marina Granovskaia said: "We are delighted to be able to add a player of Thiago Silva's proven world-class credentials to our squad.
"Having performed at the highest level for many years, we have no doubt his experience and quality will complement the many exciting talents we already have here.
"Thiago will be an excellent fit and we hope he can add some new trophies to his impressive list of honours."