Tuchel has signed an 18-month contract, with the option of a further year, to become Roman Abramovich’s 13th different manager during a little under 18 years in charge.
Lampard was shown the door on Monday after just one and a half seasons in charge thanks to a downturn in form that had seen the Blues slip from top spot to ninth in the Premier League table.
Tuchel won back to back titles with PSG and also took the Ligue 1 club to last season’s Champions League final, but was relieved of his duties in December and replaced by former Tottenham boss Mauricio Pochettino.
Prior to that, the German had been manager of Borussia Dortmund and Mainz in his homeland, having taken over from now Liverpool manager Jurgen Klopp in both roles.
More to follow.