The 1999–2000 Appalachian State Mountaineers men's basketball team represented Appalachian State University in the 1999–2000 NCAA Division I men's basketball season.

The Mountaineers, led by fourth-year head coach Buzz Peterson, played their home games for the final season at the Varsity Gymnasium in Boone, North Carolina as members of the Southern Conference.

The team finished the season with a record of 23–9 and 13–3 in SoCon play.

14 seed in the South region, they lost to No.

3 seed Ohio State in the opening round.