Detroit trailed by 21 points in the first half, but came back to win its second straight. The Pistons had not rallied from that large a deficit to win a game since 2008.
The 3-pointer by Jennings with 47 seconds left put Detroit in front by two and the only scoring after that came when Jared Sullinger made 1-of-2 from the line for the Celtics with 42 seconds remaining.
Jeff Green missed a layup in the final second that would have given Boston the win.
Jennings scored 28 points and dealt out 14 assists. Josh Smith added 20 points for the Pistons in what was their sixth win in their last seven road games.
Sullinger led Boston with 19 points.