Thunder General Manager Sam Presti announced the signing Tuesday but did not disclose terms of the deal.
The Thunder first signed Shakur to a 10-day contract on March 15. He did not play in five games with the team and was released last Thursday. Shakur then returned to play for the Tulsa 66ers.
The 6-foot-3 Shakur has averaged 20.4 points, 7.1 assists, 4.6 rebounds and 2.3 blocked shots per game this season for Tulsa while shooting 49.8 percent from the field.
Shakur went undrafted out of Arizona in 2007 and has played overseas in Poland, Spain and Greece in recent years.