The final play wasn't designed to go to Knight but the second-year guard took the ball from Tayshaun Prince and found a seam in the defense to score the winning basket.
"The play wasn't set up for me to get him the ball but he was patient enough to relax and make a play out of it," Prince said.
Kyle Lowry missed a 20-footer at the buzzer for Toronto.
Greg Monroe had 19 points and 11 rebounds for the Pistons, who looked sharp in crunch time two days after falling flat in the second half at Orlando. Knight and Prince scored 16 apiece.
"With such a young group, I liked the way we composed ourselves," coach Lawrence Frank said. "We're happy with the poise our guys showed down the stretch."
Drummond played nearly the entire fourth quarter and had six of his eight offensive rebounds in the final period. He finished with 13 points and 13 boards.
"Andre was huge," Frank said. "All this is new to him, so it's interesting to see how he's going to react."
Drummond played a season-high 24 minutes and led the Pistons to a 15-9 edge on the offensive glass. He also helped defend Andrea Bargnani late in the game.
"Not just because it was a key moment, but it's just good being out on the floor trying to help the team win," Drummond said.
Bargnani scored a season-best 34 points and Lowry added 19 for the Raptors, who have dropped three in a row.
"It looks like the last play was the reason and it was not," Toronto coach Dwayne Casey said. "It was the 15 offensive boards."
The Pistons led 47-43 at halftime and increased their advantage to as many as 13 points after a 16-5 run early in the third quarter.
Lowry scored eight points during a 10-0 spurt that helped the Raptors close to 72-68 by the end of the period, and Toronto moved in front in the fourth by scoring eight consecutive points during one stretch.
Detroit made just two of its first 14 field-goal tries in the final period but never fell behind by more than five. It trailed 90-87 with less than a minute left but Prince made a hook shot to cut the deficit to a point and set the stage for Knight's big play.
Toronto C Jonas Valanciunas appeared to turn his left ankle midway through the third quarter but returned a few minutes later. ... Members of Divine Providence Lithuanian Catholic parish in suburban Southfield reserved two sections of seats and turned out in the colors of the nation's flag to root on countrymen Valanciunas and Linas Kleiza of the Raptors.