Blues general manager Doug Armstrong announced the deal Wednesday.
The 43-year-old Brodeur played seven games for St. Louis this season, retiring Jan. 29 to become a senior adviser to Armstrong. Brodeur played 21 seasons for New Jersey, leading the Devils to three Stanley Cup titles and winning the Vezina Trophy four times as the NHL's top goalie.
Brodeur leads NHL goalies in career victories with 691, shutouts with 125, games with 1,266 and minutes with 74,438. He's also first in playoff starts with 204 and shutouts with 24.