Coreau will report to the Blues' American Hockey League (AHL) affiliate, the San Antonio Rampage.
Coreau, 27, has dressed in 13 games with the AHL's San Diego Gulls this season, posting a 3-6-2 record to go along with a 3.57 goals-against average and a .895 save percentage.
During his AHL career, the 6-foot-6, 220-pound goaltender has accumulated an 88-54-12 regular-season record and captured the 2017 Calder Cup with the Grand Rapids Griffins.
A native of Perth, Ontario, Coreau has also appeared in 21 career NHL regular-season games, tallying a 5-9-4 record.