John Mabry's journey in Major League Baseball began when he was drafted by the St. Louis Cardinals in the sixth round of the 1991 MLB Draft. He made his major league debut with the Cardinals on April 23, 1994. Mabry, primarily an outfielder and first baseman, quickly established himself as a reliable player with a solid left-handed bat.

During his initial stint with the Cardinals, Mabry demonstrated his ability to contribute both offensively and defensively. In 1996, he had one of his best seasons, hitting .297 with 13 home runs and 74 RBIs. His performance helped the Cardinals reach the National League Championship Series that year. Mabry's versatility allowed him to play multiple positions, which made him a valuable asset to the team.

In 1998, Mabry was traded to the Seattle Mariners, where he continued to be a consistent performer. Over the next few years, he played for several teams, including the Philadelphia Phillies, Oakland Athletics, Florida Marlins, and San Diego Padres. Mabry's adaptability and steady performance made him a sought-after player for teams looking to bolster their rosters.

Mabry returned to the Cardinals in 2001, providing veteran leadership and depth to the team. He played a key role in the Cardinals' success during the early 2000s, including their run to the World Series in 2004. Although the Cardinals fell short against the Boston Red Sox, Mabry's experience and presence in the clubhouse were invaluable.

In 2005, Mabry was traded to the Chicago Cubs, where he continued to contribute as a utility player. His ability to play multiple positions and deliver clutch hits made him a valuable member of the Cubs' roster. Mabry's career came full circle when he returned to the Cardinals for a third stint in 2007, his final season in the majors.

Throughout his career, Mabry was known for his professionalism and work ethic. He played in over 1,000 major league games, finishing with a career batting average of .263, 96 home runs, and 446 RBIs. After retiring as a player, Mabry transitioned to coaching, serving as the hitting coach for the St. Louis Cardinals from 2012 to 2018.