He was also unanimously chosen as the Freshman of the Year, joining Marcus Smart, Michael Beasley and Kevin Durant as the only players to earn both honors.
He is the seventh Oklahoma State player to win the award.
The Arlington, Texas native was also a unanimous selection to the All-Big 12 First Team, All-Freshman and All-Newcomer teams.
Cunningham led the league in scoring, both in conference games (20.1 points per game) and overall (19.7 points). He is up for the John R. Wooden Award as the NCAA Player of the Year, a finalist for the Bob Cousy Point Guard Award and a Naismith Trophy semifinalist.
He was also named the Oscar Robertson National Player of the Week when he dropped 40 points and grabbed 11 boards to lead Oklahoma State to an overtime defeat of Oklahoma, then ranked No. 7. He was a nine-time conference Player of the Week.
With 19.7 points, 6.3 rebounds, 3.5 assists, 1.4 steals and 1.0 blocks per game, Cunningham posted a stat line that has been matched by four players from power conferences over the past 20 years, per the league's release.
The 12th-ranked Cowboys will play No. 10 West Virginia in the Big 12 Tournament on Thursday, though it's unclear if Cunningham, who rolled his ankle and missed the team's win over West Virginia over the weekend, will be on the court.