Keaton Ward, making his 100th appearance for the club, opened the scoring with aplomb in the 10th minute and although Luke Hannant equalised six minutes later, substitute James Gale won it for the Pilgrims 10 minutes before the break.
Gateshead's Kenton Richardson went close with two late headers, but United held on to spark jubilation amid another bumper home attendance.
The Pilgrims were afforded the best possible start when WARD intercepted a stray pass from Gateshead's Jamie Bramwell to run through unopposed to blast past an exposed George Shelvey.
United's lead was short-lived though and with the home defence all drawn across to deal with Jovan Malcolm, HANNANT was afforded the freedom of the penalty area to finish the eventual cross from the Heed left.
United lost the services of top scorer Hazel to a knee injury but his replacement GALE made his mark less than three minutes after emerging as a sub - beating Shelvey with a firm drive after advancing on to Dylan Hill's neat flick following Greg Sloggett's initial excellent play.
Gregory stuck up a big left arm to keep out Malcolm's angled header towards the break, while Brad Nicholson timed his challenge perfectly to stop the marauding Frank Nouble after half-time.
Richardson headed a Regan Booty corner against the post, before diverting a Ben Worman flag-kick wide of the other post, as United survived plenty of late Gateshead pressure to record their biggest three-point haul of the campaign.
Boston (3-4-2-1): Cameron Gregory; Connor Teale, Zak Mills, Brad Nicholson; Jai Rowe, Jordan Richards, Greg Sloggett, Cameron Green; Dylan Hill, Keaton Ward (Olly Green 85); Jacob Hazel (James Gale 32). Subs (not used): Adam Marriott, Noah Wadsworth, Jimmy Knowles, Jacob Scott, Jake Lovelace (gk).
Gateshead (3-4-2-1): George Shelvey; Kenton Richardson, Jamie Bramwell, Joe Grayson; Luke Hannant, Regan Booty, Tim Akinola (Tyrelle Newton 70), Branden Horton (Tyrell Sellars-Fleming 89); Liam Humbles (Ben Woman 70), Jovan Malcolm; Frank Nouble. Subs (not used): Ryan Bartley, Charlie Colkett, Brayden Johnson, Tiernan Brooks (gk).
Referee: Paul Marsden.
Attendance: 3,401 (146 visitors).
PIC: Chris Bray.