The Portuguese had signed a contract with the club till 2023.
The former Chelsea and Manchester United boss is a three Time English Premier League winner and has been active as a pundit on Sky sports since his exit from United.
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Having decided it was time to act, Spurs chairman Daniel Levy drew up a shortlist which included Mourinho, RB Leipzig’s Julian Nagelsmann, former Juventus boss Max Allegri and PSG’s Thomas Tuchel.
Negotiations between Spurs and Mourinho – who had been out of work since he was sacked by United in December – intensified over the last few days and concluded in the early hours of Wednesday morning.
Mourinho was promised funds to improve the squad in January and in the summer transfer window, if he felt necessary.
“I am excited to be joining a club with such a great heritage and such passionate supporters,” said Mourinho. “The quality in both the squad and the academy excites me. Working with these players is what has attracted me.”
He will take training at Hotspur Way on Wednesday ahead of his first game on Saturday – against West Ham at the London Stadium.