"I am excited to be joining a Club with such a great heritage and such passionate supporters," Mourinho told Spurs' official website. "The quality in both the squad and the academy excites me. Working with these players is what has attracted me."
Chairman Daniel Levy added: "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 are the Portuguese's third Premier League club, having won three top-flight titles in two spells with Chelsea before lifting the EFL Cup and UEFA Europa League trophies in two-and-a-half years at Manchester United.
He started his managerial career at Porto, winning the UEFA Europa League and Champions League in successive seasons before taking over at Chelsea in 2004. After back-to-back Premier League titles in three years at Stamford Bridge he moved to Inter Milan and won the Champions League in a treble-winning 2009/10 season at San Siro.
Mourinho subsequently managed Real Madrid to the LaLiga title, before returning to Chelsea to lift the 2014/15 Premier League Trophy.
The 56-year-old then took charge of Man Utd between May 2016 and December 2018.
Mourinho will make his managerial debut with Spurs when they travel to West Ham United on Saturday.
They are looking to improve upon their current position of 14th and ending a five-match winless run.
Spurs have confirmed that Joao Sacramento has been appointed as assistant head coach from League 1 side Lille.
Nuno Santos moves from the French club to become their new goalkeeper coach.
Carlos Lalin has been named the north Londoners' fitness coach, while tactical analyst Ricardo Formosinho and technical analyst Giovanni Cerra join Mourinho at Tottenham Hotspur Stadium.