Jose Mourinho was on Wednesday appointed Tottenham's new manager to replace the sacked Mauricio Pochettino, with the club languishing 14th in the Premier League.
The Portuguese former Chelsea, Real Madrid and Manchester United manager signed a contract until the end of the 2022/23 season, the north London club said in a statement.
Pochettino, 47, transformed Spurs' fortunes after arriving from Southampton in 2014 and although he failed to win a trophy he took the club to the Champions League final for the first time in their history just six months ago.
But the Argentine was sacked on Tuesday, with Tottenham struggling in the league after picking up just three wins from their opening 12 games.
This season they were knocked out of the League Cup by fourth-tier Colchester United and suffered an embarrassing 7-2 defeat at home to Bayern Munich in the Champions League.
"I am excited to be joining a club with such a great heritage and such passionate supporters," said Mourinho, who has won domestic titles in a record four different countries.
"The quality in both the squad and the academy excites me. Working with these players is what has attracted me."
Spurs Chairman Daniel Levy said: "In Jose we have one of the most successful managers in football. He has a wealth of experience, can inspire teams and is a great tactician.
"He has won honours at every club he has coached. We believe he will bring energy and belief to the dressing room."
Spurs hailed their new boss, saying in their statement: "Jose is one of the world's most accomplished managers having won 25 senior trophies."
He won Champions League titles with Porto and Inter Milan.
The 56-year-old Portuguese won three Premier League titles over two spells in charge of Chelsea and returned to England to manage Manchester United in 2016.
Mourinho was sacked last December following a poor run of results and has been out of work since, most recently working as a TV pundit.
His first match in charge will be the London derby away to West Ham on Saturday.