The 51-year-old has agreed a three-year contract following extensive talks with co-owners Todd Boehly and Behdad Eghbali, and will immediately start planning for next season.
An official announcement is expected in the coming days and Pochettino will take over for pre-season this summer.
He is currently in Barcelona but the former Tottenham manager will return to London, where caretaker boss Frank Lampard will make himself available as a sounding board to help ensure a smooth transition for the incoming Chelsea head coach.
Pochettino is expected to be joined by his long-time assistant Jesus Perez, coach Miguel D'Agostino, goalkeeping coach Toni Jimenez and his son Sebastiano, who is a sports scientist. He still has a house in north London but may want to live closer to the Chelsea training ground in Cobham.
Pochettino wants to sign a striker and a goalkeeper this summer, in line with Chelsea’s existing transfer plans, and will start work straightaway on reducing the size of the squad and deciding which players he wants to sell.
He will ask Chelsea to restart contract talks with Mason Mount, who is a target for Liverpool. The midfielder is out of contract at the end of next season and is not close to agreeing an extension after talks with Boehly showed no sign of a breakthrough.
If Mount does not agree a new contract this summer, Chelsea are ready to sell the England international and have valued him at £70million. Chelsea also need to make a decision over the futures of N'Golo Kante, whose contract expires at the end of the season, and a host of other players in the squad.
Mateo Kovacic could leave amid interest from Manchester City, Manchester United and Bayern Munich. Pochettino could also look at signing a new midfielder but that will depend on player sales.
He will oversee a mass clear-out of the Chelsea squad as the club look to offload players to ensure they continue to stay in line with Financial Fair Play (FFP) rules.
Chelsea need to sell players to balance the books after spending more than £600m since they were taken over by Boehly and Clearlake Capital last year.
The club is under pressure to offload players before June 30 so the sales can be included in their financial accounts for 2022-23, and deciding who Pochettino wants to sell will be a priority in talks with co-sporting directors Paul Winstanley and Laurence Stewart.
Pochettino has been out of work since leaving Paris Saint-Germain after winning the Ligue 1 title at the end of last season. He has never been subject to an offer from Tottenham to return to his former club, who are also looking for a new manager.
Pochettino will take over a Chelsea team who will not be playing in Europe next season. The Blues are currently 11th in the Premier League table after Saturday’s 2-2 draw with Nottingham Forest at Stamford Bridge.
They face a tricky final three games, away to Manchester City and Manchester United before hosting Newcastle, and are in danger of their lowest League finish since 1993-94 (14th).