The refs called 61 fouls and five players fouled out. Pangos made 12 of 14 free throws, including 10 of 10 in the last 1:31. The final 3 1/2 minutes took 24 minutes to play. It was seven off the record for fouls in a tournament game set by Iowa and Morehead State in a regional semifinal game in 1956.
The Bulldogs (29-6), in their 16th straight NCAA tournament, will play top-seeded Arizona on Sunday.
Smart had 23 points, 13 rebounds, seven assists and six steals for Oklahoma State (21-13). He was 12 of 19 from the line.
Smart is projected to be a high NBA draft pick. He passed up the NBA draft last year, in large part because the Cowboys lost to Oregon in their NCAA tournament opener. The Cowboys won five of seven games coming in, a run that coincided with Smart's returning from a three-game suspension for shoving a Texas Tech fan.
The Cowboys were called for 33 fouls, with Le'Bryan Nash, Kamari Murphy and Leyton Hammonds fouling out. The Zags made 26 of 41 free throws. The Zags were called for 28 fouls, with Sam Dower Jr. and Kyle Dranginis fouling out. The Cowboys made only 22 of 37 from the stripe.
Gonzaga big man Przemek Karnowski hurt the Cowboys inside, with 15 points and 10 rebounds. Dranginis scored 12.
Markel Brown scored 20 for Oklahoma State and Phil Forte had 12.
The Cowboys whittled a 10-point deficit down to three with 11:24 to go before Bell hit a 3-pointer for a 56-50 lead with 11:08 to go. Pangos made a layup and Brown answered for the Cowboys. Karnowski hit the front end of a one-and-one and Pangos hit a 3-pointer for a 10-point lead with 7:46 left.
Gonzaga led 43-34 at halftime, getting consecutive 3-pointers from Drew Barham and Kevin Pangos in the closing minutes.
Oklahoma State coach Travis Ford was whistled for a technical foul with 11.1 seconds left. Pangos missed the first free throw and made the second. Ford had been on the refs ever since the Cowboys were whistled for six fouls and a traveling call in a span of 1:40 midway through the half.
Gonzaga went on an 8-2 run to take a 33-24 lead, making five of six free throws and getting a 3-pointer from Dranginis.
Oklahoma State then went on a 9-1 run to pull to 34-33. Smart had two free throws and a jumper.
Gonzaga pulled away on an inside shot by Dower, the two 3-pointers and a free throw by Pangos on the technical.
Bell made two 3-pointers in the first 50 seconds and hit two other shots to help Gonzaga take a 17-6 lead.
Smart started and ended a 10-0 run that pulled the Cowboys within one point. He was fouled by Bell while making a 3-point shot and made the free throw. Murphy hit a jumper and Brown made two free throws before Smart had a tip-in.