His return to professional baseball came in 1913, when he joined the St. Louis Browns as the personal assistant of owner Robert Hedges. Three years later with the Browns sold, Rickey joined the St Louis Cardinals as field manager and later as the club's general manager. His greatest achievement, in twenty-six years with the Cardinals, was the creation of the minor league farm system.

The farm system was a training ground for new/young players; there young players were specifically groomed for the major league team. Rickey was able to produce championship teams as well as sell their surplus of talent to rival organizations. The farm team is now a staple of all major league teams.

Rickey was very systematic in searching for, and choosing, the first player to integrate the major league. He understood that the athlete not only had to be exceptionally talented but he also had to have the mental toughness to withstand the inevitable racial pressures from fans, players and coaches.

When Rickey signed Robinson to a minor league contract, August 28, 1945, for $600 per month plus a $3500 bonus, both men were forever linked in baseball's, indeed America's history.