On July 3, 2006, he signed a one-year, $2 million contract with the St. Louis Blues. During his time with the Blues, Guerin played on a line with his former Oiler teammate Doug Weight. Guerin played 1 season with the Blues. He scored 61 goals and recorded 47 points. Guerin was chosen to play in the 2007 All-Star Game, which was hosted by the Dallas Stars. Even though he was criticized for his play in Dallas, Guerin was still given a standing ovation from the fans. He became the 214th NHL player to play in 1,000 games on February 2, 2007.