The Pilgrims trailed 2-0 against the Cobblers, but second half goals from Leon Squire and Karolis Andriulionis pulled Steve Welsh’s side back into the contest.
The match concluded United’s away fixtures for the season, with a home clash against Corby Town remaining to be played.
Boston (3-5-2): Jamie Bradley; Josh Spencer, Billy Hodgkiss, Joe Cain; Daniel Worthington, Miles Lynch (Karolis Andriulionis 46), Aaron Eyett, Corey Newman, Bradley Easey; Liam Moran (Steven Dovey 46), Leon Squire.