Despite being a projected lottery pick after a successful Freshman year, Warren stayed at OU, hoping to be the primary option with Griffin leaving for the draft.

Throughout an injury-plagued Sophomore year he averaged over 16 points, 4 assists, 3 rebounds and just over 1 steal a game while shooting above 30% from 3-point range .

At the end of his sophomore season, Warren decided to forgo his last two years of eligibility, signing with an agent and declaring for the 2010 NBA draft.

[4] In August 2012, Warren signed with Maccabi Rishon LeZion of the Israeli Super League for the 2012–13 season.

[7] On March 4, 2014, he signed with Virtus Bologna of Italy for the rest of the 2013–14 Lega Basket Serie A season.

On August 13, 2017, Warren signed with Petrochimi Bandar Imam of the Iranian Basketball Super League.