Chelsea hired Mauricio Pochettino as their new manager on Monday as the Argentine accepted the daunting task of reviving the troubled Premier League club.
Pochettino agreed a two-year contract with an option for an additional year and will return to the Premier League four years after being sacked by Chelsea's London rivals Tottenham.
The 51-year-old had been out of work since being dismissed by Paris Saint-Germain in July 2022.
"Mauricio is a world-class coach with an outstanding track record. We are all looking forward to having him on board," Chelsea co-owners Todd Boehly and Behdad Eghbali said in a statement.
Pochettino, who will begin his new role on July 1, replaces Frank Lampard after the former England midfielder returned to Chelsea as caretaker boss until the end of the season.
Lampard was Chelsea's third manager of a dismal campaign that featured Boehly sacking Thomas Tuchel in September and then axing his successor Graham Potter in April after less than seven months in charge.
Pochettino emerged as the favourite after Chelsea held talks with the former Spain manager Luis Enrique and Julian Nagelsmann, who was sacked by Bayern Munich in March.
Pochettino verbally agreed to take charge at Chelsea in April, but the appointment was put on hold until the end of the season.
With the Blues wrapping up their lacklustre Premier League campaign with a draw against Newcastle on Sunday, Pochettino flew into England to officially seal the deal.
Laurence Stewart and Paul Winstanley, Chelsea's co-sporting directors, said: "Mauricio's experience, standards of excellence, leadership qualities and character will serve Chelsea Football Club well as we move forward.
"He is a winning coach, who has worked at the highest levels, in multiple leagues and languages. His ethos, tactical approach and commitment to development all made him the exceptional candidate."
Pochettino will arrive at Stamford Bridge to find a club in crisis after ending the season 12th in the Premier League -- their first bottom-half finish since 1996.
They also lost to Manchester City in the FA Cup and League Cup and made a limp Champions League quarter-final exit against Real Madrid.
Believed to be keen to sign a new goalkeeper, central midfielder and striker, Pochettino has a big job on his hands.
Just two years after Tuchel led the Blues to Champions League glory, Chelsea face a rare season without European football.
Boehly reportedly told his players their season had been "embarrassing" after a home defeat against Brighton that featured fans shouting abuse at the American.
Boehly has come under fire after overseeing a haphazard £550 million ($679 million) spending spree on new signings.
That record outlay failed to fix Chelsea's numerous issues and left them with such a bloated squad that there weren't even enough places in the changing rooms for every player to have their own seat.
Pochettino will have to fix the fractured morale among a squad packed with frustrated stars keen to leave after failing to secure regular game-time.
Lampard admitted after his final game on Sunday that standards in Chelsea's squad had slipped dramatically at a club that last won the Premier League in 2017.
Chelsea fans quickly grew tired of Potter and it will be intriguing to see if Pochettino's history with Tottenham proves a source of angst among the Blues faithful.
At least Pochettino knows what it takes to succeed in the Premier League after leading Tottenham to four top-four finishes during his five-year reign in north London.
The demanding Argentine, who first managed in the Premier League with Southampton from 2013 to 2014, also took Tottenham to their maiden Champions League final appearance in 2019.
They were beaten by Liverpool in the final but although Pochettino was unable to end Tottenham's long trophy drought, it was still a surprise when he was sacked just months after that memorable Champions League run.
He was hired by PSG in January 2021, failing to win the Ligue 1 title in his first season, while leading the club to victory in the Coupe de France.
While PSG were crowned French champions in Pochettino's second season, their disappointing Champions League last 16 exit played a major role in his dismissal and replacement by Christophe Galtier last July.