Spurs also announced the signing of Spain under-21 midfielder Yago Falque from Juventus on a season-long loan.
Adebayor, who played for Spurs's bitter North London rivals Arsenal before joining City in 2009, spent part of last season on loan at Real Madrid.
The 27-year-old has been squeezed out of City coach Roberto Mancini's plans amid an abundance of attacking riches in the form of Sergio Aguero, Mario Balotelli, Carlos Tevez and Edin Dzeko.
Spurs, who announced the signing on their website, take on Adebayor's parent club in the league on Sunday.
Adebayor's arrival at White Hart Lane bolsters coach Harry Redknapp's attacking options and if he can find his scoring touch quickly it would go some way towards winning over Spurs fans who may take some convincing because of his Arsenal past.
"He's a good talent," local media quoted Redknapp as saying earlier this week. "He could come in and be a big success.
"He's got to get back to the form he showed at Arsenal and Real Madrid."
During his loan spell at Jose Mourinho's Real last season he scored two goals against Spurs in a Champions League quarter-final first leg in April.
Adebayor started his career in France with Metz and AS Monaco before joining Arsenal in 2006.
He scored 62 goals in 142 appearances in all competitions with Arsene Wenger's side before moving to City on a five-year contract in 2009 for a fee of around 25 million pounds.
