List of Major League Baseball wins records

The following is a listing of pitching win and winning percentage records in Major League Baseball. All teams are considered to be members of the American or National Leagues, unless noted. Players denoted in boldface are still actively contributing to the record noted. An (r) denotes a player's rookie season.

0.650 win–loss percentage, career
see notes2 3

0.875 winning percentage, season
see note5