The 2004–05 Oklahoma State Cowboys basketball team represented Oklahoma State University as a member of the Big 12 Conference during the 2004–05 NCAA Division I men's basketball season.
The team was led by 15th-year head coach Eddie Sutton and played their home games at Gallagher-Iba Arena.
The Cowboys followed the previous season’s Final Four appearance by finishing with a record of 27–6 (11–5 Big 12) and a No.
7 seed Southern Illinois to reach the Sweet Sixteen.
The run ended in the regional semifinal, as Arizona defeated OSU 79–78.