Xavier Johnson added 20 points and nine rebounds for Colorado (17-6, 6-4 Pac-12), which swept the season series with the Cougars. The Buffaloes won at Washington State 71-70 in overtime last month.
DaVonte Lacy, who missed the first meeting with a rib injury, scored a career-high 34 points for Washington State (9-13, 2-8). He also connected on a career-high eight 3-pointers.
Ike Iroegbu added 10 points for the Cougars, who remain winless in five conference games on the road.
Up by three at the half after a sluggish opening by both teams, Colorado got its offense going behind a torrid second half start by Booker, who had 21 of his points in the closing period.
He scored 12 of the Buffaloes' first 13 points in a four-minute stretch opening the period and Colorado surged to 34-23 lead with 16:01 left to play. Booker punctuated the flurry with four straight field goals for Colorado, including a breakaway dunk off of a steal.
Lacy connected on his fifth 3-pointer to stall Colorado's momentum but Booker hit a jumper before Johnson countered a layup Iroegbu by converting a three-point play.
The Cougars, who trailed by 15 after a layup by Johnson, fought back to within 60-53 on a dunk Junior Longrus with 1:15 left to play.
Lacy then hit a pair of 3-pointers in the waning seconds, pulling the Cougars to 66-63 with six seconds remaining. Booker was fouled an instant after the inbounds but he made both free throws with two seconds left to secure Colorado's victory.
Colorado was held to a season low at home in points in the first half but got a 3-pointer and a layup from Johnson around a layup by Jordan Railey late in the period to take a 23-20 lead.
Benefiting from a 9-0 run early on, the Buffaloes led 15-7. But Washington State got right back in it with three 3-pointers in a five-minute stretch, including two by Lacy to help even the score at 18-all with 3:57 left in the first half.