Carey, a sophomore, rushed for a conference-record 366 yards against the Buffaloes on just 25 carries. He also caught two passes for 34 yards, and scored five touchdowns in Arizona's 56-31 victory.
Carey's 400 all-purpose yards broke a school record. He is the sixth Wildcat to win a Player of the Week Award this season but first to do so on offense.
Other nominees for the award were quarterbacks Marcus Mariota of Oregon and Brett Hundley of UCLA, as well as running back Christian Powell from Colorado, Stepfan Taylor from Stanford, Curtis McNeal of USC and Bishop Sankey of Washington.
The Wildcats, who are now 6-4 (3-4) on the season, travel to face the Utah Utes Saturday.