The right-back has signed a five-year contract at the Etihad and will wear the number two shirt.
It is understood that the two clubs agreed an initial £50m fee, with potential add-ons that could see the total rise to £53m.
“I am thrilled to be signing for City and can’t wait to get started,” Walker told City's official website. “Pep Guardiola is one of the most respected managers in the world and I feel he can help me take my game to a new level.”
City spent months in negotiation with Tottenham for Walker after identifying him as the solution to their long-standing problems at right-back, but were initially reluctant to meet the north London club's hefty asking price.
However, after missing out on free agent and Pep Guardiola favourite Dani Alves, who joined Paris Saint-Germain on Wednesday, City came under pressure to finalise a deal for the England international.
Walker has developed into one of the Premier League's leading full-backs under Mauricio Pochettino over the last few years, but lost his starting place towards the end of last season after a falling-out with the Argentinian.
After being replaced in the side by understudy Keiran Trippier, Walker informed Tottenham that he wished to leave the club. His arrival at City means he could face his former team-mates as soon as 29 July, when the two clubs meet in Nashville, Tennessee for a pre-season friendly.
Txiki Begiristain, City's director of football, said: “Kyle is a fine full-back, one capable of producing quality at both ends of the pitch.
“We’ve followed his progress at Tottenham and have been really impressed by how he has developed. He is now one of the best right-backs in the Premier League and justifiably an England regular.
“I am sure he will be a success at Manchester City this season and beyond,” he added.
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