Kerr was represented in negotiations by Priority Sports' Mike Tannenbaum, former general manager of the New York Jets.
"It just came down to a personal decision," said Priority CEO Mark Bartelstein, who served as Kerr's agent throughout his playing career. "These are two great jobs. There were no problems with the Knicks. This was not about what the Knicks did or didn't do. This was about Steve, in his heart, deciding that Golden State was a better fit right now for him and his family. Phil was great. First class in every way."
"It was a long process, and Steve went through a lot of different feelings," Tannenbaum said. "And there wasn't any magical moment where he made the decision. The more he thought about it, the more he just felt that everything about Golden State felt right to him."
The Warriors met Tuesday with Kerr before his TNT broadcast in Oklahoma City and appeared to remain in the running for him alongside the Knicks, according to sources with knowledge of the situation.
Sources told ESPN.com that the Warriors, after initially believing they had no shot at Kerr because he was "too deep" into his negotiations with the Knicks, started pressing him as hard as they could to try to change his mind after Golden State's other top coaching target -- Van Gundy -- struck a deal with the Pistons.
The Knicks, sources said, had been strong favorites to land Kerr, largely because of his longstanding relationship with Jackson.
Golden State, though, offered a roster headlined by star guard Stephen Curry and the ability for Kerr to take over a 51-win team in his home state. Kerr is a Southern California native and has lived in San Diego for years.
Kerr replaces Mark Jackson, who was fired after the Warriors' first-round loss to the Los Angeles Clippers in seven games in the wake of mounting tension between him and the front office.
The Knicks must now regroup after centering their initial search for Mike Woodson's replacement on Kerr. But sources with knowledge of the situation said that Oklahoma City guard Derek Fisher and Lakers assistant coach Kurt Rambis, both of whom are close to Phil Jackson, are likely to be considered.
Last week in Los Angeles, Fisher was asked about coaching the Los Angeles Lakers.
"I would tell people to allow me to finish my career as a player before they give me another job after that," Fisher said, while calling it "humbling."
"Just to think about people thinking of me in that manner -- especially while I'm still playing," Fisher said. "I promise you this is the last thing on my mind at this point. I really haven't thought about it that much. Hopefully there's a lot of basketball left to be played this season for sure. Once that's done we'll go from there."
Information from ESPN.com's Marc Stein, ESPN.com's Ramona Shelburne, ESPNNewYork.com's Ian Begley, ESPNNewYork.com's Ian O'Connor and The Associated Press was used in this report.