The 2008–09 Dayton Flyers men's basketball team represented the University of Dayton during the 2008–09 NCAA Division I men's basketball season.

The Flyers, led by sixth year head coach Brian Gregory, played their home games at the University of Dayton Arena and were members of the Atlantic 10 Conference.

They finished the season 27–8, 11–5 in A-10 play for a tie for second-place.

They received an at-large bid to the NCAA tournament where they defeated West Virginia in the round of 64 before losing in the round of 32 to defending national champion Kansas.

The 2007–08 Dayton Flyers finished the season with an overall record of 23–11, with a record of 8–8 in the Atlantic 10 regular season for a tie for a fifth-place finish.