The Mets traded Neil Walker and cash to the Milwaukee Brewers for a player to be named later, the Brewers announced.
Ken Rosenthal of Fox Sports was the first to report on Saturday that a deal was imminent.
Walker was participating in batting practice on Saturday and was in the lineup at second base, but was scratched shortly before the game started. He was replaced at second base by Jose Reyes.
Walker has played the majority of his games this season at second base, but has played three games at first base and two games at third base.
RHP Kevin McGowan will replace Walker on the 40-man roster, per MLB.com's Anthony DiComo. In Triple-A Las Vegas this season, he is 5-4 with a 4.06 ERA and four saves in 44 games this season.
The 31-year-old hit .264 with 10 home runs, 13 doubles, and 36 RBIs in 73 games this season. Walker hit .282 with 23 home runs in 113 games last year in his first season with the Mets.