Chelsea appointed Mauricio Pochettino as head coach on Monday, tasking the former Tottenham Hotspur and Paris St Germain manager with reviving their fortunes after a dismal season.
Chelsea finished 12th in the Premier League on Sunday following a chaotic campaign during which Thomas Tuchel, Graham Potter and Frank Lampard had spells in charge of the London club.
Argentine Pochettino, who has signed a two-year contract with the option of a further year, will start work on July 1.
He was linked with the Chelsea job last year when they sought a permanent replacement following the dismissal of Tuchel, but they opted to appoint Brighton & Hove Albion's Potter.
The 51-year-old Pochettino will become the third permanent Chelsea manager since their sale in 2022 to a consortium led by LA Dodgers part-owner Todd Boehly and backed by Clearlake Capital, a private equity firm.
"Mauricio is a world-class coach with an outstanding track record. We are all looking forward to having him on board," Chelsea's owners Boehly, Behdad Eghbali, Jose E Feliciano, Mark Walter and Hansjorg Wyss said in a statement.
At the time of Lampard's appointment, Boehly and Eghbali said the ex-Chelsea midfielder was brought in on an interim basis so the club could conduct a "thorough and exhaustive process" to hire a permanent manager.
Chelsea lost eight of their 11 matches under Lampard, who took over at Stamford Bridge last month after the sacking of Potter, and missed out on European football for next season after their quarter-final exit from the Champions League.
The London club won the Champions League in 2021, but ended this season without any silverware and stumbled towards their worst campaign since 1993-94 - when they finished 14th under Glenn Hoddle - despite their new US owners' huge outlay on players.
Pochettino, who favours a high-pressing and attacking style of play, garnered a reputation for fostering young talent and led Southampton to an eighth-placed finish in his first full season in England before joining Spurs in 2014.
Tottenham reached the 2019 Champions League final and became Premier League contenders as they finished in the top four for four straight seasons from 2015-19 before he was fired.
Pochettino joined PSG in January 2021, winning a French Cup and a Ligue 1 title, but he was sacked after failing to deliver in the Champions League.
His staff at Chelsea will include Jesus Perez, Miguel d’Agostino, Toni Jimenez and Sebastiano Pochettino.
"Mauricio's experience, standards of excellence, leadership qualities and character will serve Chelsea Football Club well as we move forward," co-sporting directors Laurence Stewart and Paul Winstanley said.
"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."