The 28-year-old striker, who had spent time on loan at Real Madrid before a spell with Spurs in 2011-12, broke the news in a celebratory tweet, promising fans that he is hungry to score more goals for the club.
"I'm back!!!! Tottenham here I come!! I'm hungry for goals...Get ready," he wrote on his official Twitter page.
After scoring 18 goals in 37 appearances for the Lilywhites last season, new boss Andre Villas-Boas was eager to add the forward to his side, with Jermain Defoe the only recognized senior striker on the squad when he took charge.
In an interview on Tottenham's official website, Adebayor spoke of his happiness to be signing with last year's fourth-placed Premier League team, expressing his ambition to excel there.
"I am pleased to be signing for Spurs on a permanent basis after finally agreeing my departure with Manchester City," he declared.
"It may have taken longer than expected but I am delighted to be back at Tottenham Hotspur. I really enjoyed my time here last season and I am hoping we can achieve great things together again."