The 52-year-old, who had previously been in charge from 2004-2007, rejoined the Stamford Bridge outfit in 2013 and led Chelsea to the league title and League Cup success last season.
"I said when I returned here that I have a special feeling for this club and nothing changed," Mourinho told the club's website (www.chelseafc.com).
"I think this is a normal thing for me to sign a new contract. It is important we have this continuity and I hope we can enjoy more success in the future -- for the fans, the players and the club.
"It is the club closest to my heart and I am very happy to know I will be staying here for a long time."
Mourinho's side won the league twice during his first spell in charge and lifted the FA Cup plus two League Cups before the Portuguese left the club and enjoyed more success at Inter Milan, who won the Champions League in 2010.
Mourinho joined Real Madrid immediately after his European triumph with Inter -- his second Champions League success after winning the trophy with Porto in 2004 -- and won the King's Cup in his first season with the Spanish giants.
Real won their first La Liga title in four years in 2012 but the next season was turbulent as dressing-room divisions with established players, such as keeper Iker Casillas and defender Sergio Ramos, left Mourinho feeling unloved in the capital.
A welcome return to Chelsea soon followed and the London club finished third in the league under Mourinho in the 2013-14 season -- four points behind champions Manchester City.
Chelsea were rampant in their quest for the title last season, however, and won the league with three matches to spare as Mourinho ensured his 69 percent win rate was the best of any manager to have taken charge of 15 or more Premier League games.
"We are very happy that Jose has committed four more years to the club," Chelsea director Marina Granovskaia said.
"Since his arrival two years ago he has carefully developed the playing squad and brought trophies to Stamford Bridge.
"We look forward to the next four years and the continued success of the team."
Chelsea begin the defence of their Premier League title at home to Swansea City on Saturday.
(Reporting by Michael Hann, editing by Ken Ferris)
Share
