The 2020–21 Appalachian State Mountaineers men's basketball team represented Appalachian State University in the 2020–21 NCAA Division I men's basketball season.

The Mountaineers, led by second-year head coach Dustin Kerns, played their home games at the George M. Holmes Convocation Center in Boone, North Carolina as members of the Sun Belt Conference.

They defeated Little Rock, Texas State, Coastal Carolina, and Georgia State to win the Sun Belt tournament.

They received the conference's automatic bid to the NCAA tournament where they lost in the First Four to Norfolk State.

They defeated Coastal Carolina in the second round of the Sun Belt tournament before losing in the quarterfinals to Texas State.