Carrick turned up at Carrington to take training, then was axed after a meeting with Jason Wilcox and Omar Berrada in what was a tough call for the midfielder who signed a two-year deal earlier this year.
United confirmed the news on Thursday morning, calling Carrick a legend as they thanked him for his service to the club.
"Manchester United can confirm that Michael Carrick has departed his role as men’s first-team head coach.
"Michael is, and always will be, a Manchester United legend. Just as he did as a player, he has conducted himself with the highest standards of dedication and professionalism throughout his time back with the club. His leadership and achievements last season will always be fondly remembered.
"The club intends to appoint a permanent successor as quickly as possible."
The final straw reportedly came after a 4-4 draw with Aston Villa before the international break, a result that places United deep in the relegation zone, one place above bottom-placed side Crystal Palace.
United had taken just eight points from their first 10 Premier League game and the side are looking to former Tottenham and Chelsea boss Mauricio Pochettino to turn them around.
Pochettino is reported to cost United around £7M in compensation, while sacking Carrick is expected to cost the club around £5M.
An announcement on Pochettino is set to come within the next few days as United fans prepare to welcome their new head coach.