The three-batter minimum will become effective for the 2020 MLB season, the league announced Wednesday.
Under the new rule, all starting and relief pitchers must face a minimum of three batters per outing unless the inning ends before that. A substitution can occur if an umpire rules a pitcher sustained an injury or illness that prevents him from continuing in the game.
The three-batter minimum will be put into use starting March 12 for Spring Training.
MLB's other rule changes include an increase from 25 to 26 players allowed on the active roster from Opening Day through Aug.