It is not yet known what Walker’s deal with the Knicks will look like in terms of year and dollars.
Walker, 31, had two years and roughly $74 million remaining on his contract with the Thunder.
He was traded from the Boston Celtics to the Thunder in June.
Walker averaged 19.3 points and 4.9 assists while playing 31.8 minutes per game in 43 contests with the Celtics last season.
Walker dealt with knee issues last season — including in the playoffs — but hopes those woes are behind him.
“I’m planning on a big summer and getting myself feeling good again,” Walker said after the Celtics were eliminated from the playoffs. “It’s been a while since I’ve really had time off. This is an important time for me.”