Saint Louis pulled within eight late in the third quarter following a 17-point deficit at halftime, but Princeton was able to come away with the 66-50 victory.
The Billikens fell to 7-4 on the season, while the Tigers improved to 11-1.
Princeton's leading scorer on the season, Bella Alarie, hit a 3-pointer at the buzzer to end the first quarter and give the Tigers an 18-11 lead after one. She finished the night with a game-high 23 points and 13 rebounds, along with two blocks and two assists.
The Tigers used a 17-2 run to end the first half, taking a 41-24 lead into the locker room.
Redshirt freshman Jaidah Stewart nailed a 3-pointer early in the third quarter, capping a 9-0 run for the Billikens and bringing them within 11 at 45-34.
Stewart, playing her first game in a SLU uniform, wrapped up the night with nine points and one assist.
Rachel Kent hit a three late in the period to pull the Billikens back to within single digits at 51-43.
Princeton outscored the Billikens 13-7 in the fourth quarter and came away with the 66-50 victory.
Sophomore Ciaja Harbison led SLU in scoring for the fourth time this season, finishing with 12 points, five assists and one rebound.
Kent recorded eight points, three rebounds and three assists.
Brooke Flowers collected her third double-digit rebounding performance of the year, tallying 10 boards, four points and two blocks.
Saint Louis is back in action Sunday at Chaifetz Arena for a 1 p.m. tip against Kansas.