The team says general manager Kavis Reed will serve as head coach until the end of the season.
Quarterbacks coach Anthony Calvillo will take over offensive co-ordinator duties while defensive line coach Greg Quick will handle the defence.
The Alouettes are 3-8, have lost four games in a row and sit third in the weak CFL East Division.
The moves come a day after team co-owner Andrew Wetenhall warned there may be changes if the club does not start winning games and make the playoffs for the first time in three years.
WATCH BELOW: New goals for Montreal Alouettes
Chapdelaine was promoted to interim head coach when Jim Popp was removed last September with the team mired in last place at 3-9.
He took them to a 4-2 record over the final six games, but it was not enough to secure a playoff spot.
The interim tag on is job title was removed after the season, and Reed was handed the general manager’s job when Popp was fired.