On March 10, 2008, Green agreed to a three-year deal worth about $9 million with the St. Louis Rams, rejoining the team he played for in 1999 and 2000. On September 23, 2008, Green was named the starter for week 4 versus the Buffalo Bills. He completed 17 of 32 passes for 236 yards with one interception and a quarterback rating of 64.1. On November 9, 2008, against the Jets, Green took over for Marc Bulger after Bulger was shut out by the Jets in the first half. The Rams released Green on February 25, 2009.