Jurrjens was signed as an undrafted free agent by the Detroit Tigers in 2003. In seven games during his 2003 campaign with the GCL Tigers, Jurrjens accumulated a 2-1 record with 20 strikeouts and just three walks. However, Jurrjens really broke out during his 2005 season with the West Michigan Whitecaps, the Tigers' single-A affiliate. In 26 games started, Jurrjens went 12-6 with 108 strikeouts and 36 walks. He continued to improve during the 2006 season, as a 5-0, 2.08 ERA start with the Whitecaps earned Jurrjens a promotion to the Erie SeaWolves, the Tigers' AA affiliate. In 12 games with the SeaWolves, Jurrjens went 4-3 with a 3.36 ERA.