Coach Andy Enfield was equally impressed with what his freshman guard did when he wasn't shooting.
"When you go 10 for 10 from the field, it's a pretty good game," Enfield said after Stewart collected 22 points, four rebounds and two blocked shots to help the Trojans defeat the Eagles, 75-71. "But he did some things today he couldn't do a month ago."
Stewart's perfect-10 shooting performance tied the record set by Taj Gibson, who went 10 for 10 against Boston College in the NCAA tournament on March 20, 2009.
Nikola Jovanovic added 16 points and nine rebounds for USC, which had never played in Chestnut Hill before.
The Trojans (7-4) won for the fifth time in six games, bouncing back from an overtime loss to Army last week.
Aaron Brown had 18 points for Boston College (6-4), which trailed by nine with 22 seconds left before scoring seven straight points in only 11 seconds. Olivier Hanlan had 15 points and eight assists, but he missed a three-point attempt that could have made it a one-point game in the final seconds.
"When they went up seven, they thought the game was over and there were 20 seconds left," Enfield said of his players.
Dennis Clifford had nine points and nine rebounds for the Eagles, who had been unbeaten at home.
The Trojans led, 72-63, with 22 seconds left before the Eagles rallied. Patrick Heckmann hit a three-pointer, and Hanlan stole the ball in the backcourt and made a layup. Katin Reinhardt made one of two free throws, then Brown made a three to make it a two-point game.
Reinhardt made two free throws with 11 seconds left, then Hanlan missed his three-point attempt with five seconds left.
"They outhustled us, which hasn't happened to us," Boston College Coach Jim Christian said. "That's our only chance to win — against anybody, not just USC."
The Eagles forced 12 turnovers in the first half and led 45-41 early in the second, before giving up 14 of the next 17 points. Hanlan ended the USC run with a three-pointer that made it 55-51 with 12 minutes left.
Up next for the Trojans
USC vs. Vermont, Tues., Dec. 30, 8:30 p.m., at the Galen Center. TV: Pac-12 Networks. Radio: 690 AM — After handing Boston College its first home loss of the season, the Trojans will host the Catamounts, who have lost two games in a row.