Washington, who did not score in the first 17 minutes, went 5 of 11 from the floor, 3 of 6 from behind the arc and 13 of 15 from the free-throw line, including 9 of 10 in the final 1:44 to help seal the victory.
Markese Tucker contributed 11 points for the Peacocks (9-18), who snapped a two-game losing streak.
The Peacocks trailed by 15 in the first half, but with the game tied at 45 with 9:18 remaining, St. Peter’s outscored Hampton 21-14 the rest of the way. The Peacocks were 13-of-25 shooting in the second half.
Du’Vaughn Maxwell had 18 points and nine rebounds, and Deron Powers and Ramon Mercado scored 11 each for the Pirates (11-15).
St. Peter’s outscored Hampton 15-4 off turnovers.