The 2018–19 Oklahoma State Cowboys basketball team represented Oklahoma State University in the 2018–19 NCAA Division I men's basketball season.

They were led by second-head coach Mike Boynton Jr.

The Cowboys were members of the Big 12 Conference and played their home games at Gallagher-Iba Arena in Stillwater, Oklahoma.

They defeated Oklahoma in the first round of the Big 12 tournament before losing in the quarterfinals to Kansas.

They were invited to the National Invitation Tournament where they defeated Florida Gulf Coast and Stanford before losing in the quarterfinals to Western Kentucky.