Westbrook was playing in his first game since the Thunder's first-round playoff series with Houston last season, when he went down with a torn meniscus in his right knee.
He missed all of the pre-season and originally was expected to sit out an additional 4-to-6 weeks, but returned early and sparkled in his debut, dishing out seven assists while going 11-of-14 from the free-throw line.
Westbrook sealed victory with four straight foul shots down the stretch.
Kevin Durant led the Thunder with 33 points with 10 rebounds.
Eric Bledsoe pumped in 26 points and dished off a career-high 14 assists for the Suns, who fell for the first time this season.