The brother-in-law of President Barack Obama, Robinson had a solid start in Corvallis, taking a program that had lost 21 consecutive Pac-12 games to an 18-win season in 2008-09.
The Beavers' results under Robinson were uneven after that, with Oregon State finishing no better than fifth in the Pac-12 in his six seasons, including 10th this year.
"I want to thank Coach Robinson and his family for their contributions to Oregon State University," Oregon State athletic director Bob De Carolis said in a statement. "This was a difficult decision, but after further evaluation, I believe it is in the best interests of our student-athletes, our basketball program and our university."
Oregon State won 21 games in 2011-12, but went 7-11 in conference to miss the NCAA tournament.
After going 14-18 in 2012-13, the Beavers were 16-16 this season, including 8-10 in the Pac-12, and lost to Radford at home in the CBI.
Robinson, First Lady Michelle Obama's brother, went 94-105 overall with Oregon State after spending two seasons as Brown's head coach.
He also served as an assistant at Northwestern under Bill Carmody, an assistant coach at Princeton during Robinson's senior season as a player.
Oregon State has not reached the NCAA tournament since 1990.