The Blues did not reveal Hull's new position, although Jeremy Rutherford of the St. Louis Post-Dispatch reports he will serve as a vice president.
The press conference will begin at Scottrade Center at 6:16 p.m. (an acknowledgement of Hull's jersey number) and will be open to the public.
In 744 career games with the Blues, Hull scored a franchise-best 527 goals and 936 points.
In 1990-91, he set a team record with 86 goals, which remains the highest NHL total for a right wing and is third all-time. The eight-time All-Star won the Hart Trophy that season as League MVP.
Hull won the Stanley Cup twice, in 1999 with the Dallas Stars and 2002 with the Detroit Red Wings. After retiring, Hull worked in the Stars front office, starting as a special assistant to the team president before briefly serving as a co-general manager alongside current assistant GM Les Jackson.
Monday's announcement will mark a return to St. Louis for Hull, 49. He left the Blues as a free agent when he signed with the Stars in 1999.