The move was announced before Tuesday night's game against the Philadelphia Phillies. Stanton was in the lineup in right field and batting seventh.
Stanton wowed the Marlins during spring training with his power, but the 20-year-old outfielder was sent to Double-A Jacksonville for seasoning. He responded by dominating the Southern League, hitting .311 with 21 homers and 52 RBIs in 52 games to earn a promotion.
Lamb hit .200 (5-for-25) with no homers and four RBIs.