Army Athletics Director Boo Corrigan said Ellerson was let go after compiling a 3-9 record this season, including a 34-7 rout at the hands of the Midshipmen Saturday.
"This is a very difficult day for all of us at West Point," he said. "Rich Ellerson has represented West Point and the Army football program extremely well since taking over as our head coach five years ago."
But, he added, "our team has not experienced the level of success on the football field that we expect, and we feel it is necessary to make a change in leadership at this time."
Ellerson finished his stint at West Point with a 20-41 record.