The Pilgrims' longest-ever journey for a competitive fixture culminated in a 3-0 defeat - with Rekeil Pyke opening the scoring for the Tinners on the stroke of half-time.
Tyler Harvey doubled the advantage from the penalty spot four minutes after the break, with Will Dean wrapping up Truro's resounding win in the 55th minute.
United were unchanged, but were missing striker Kieren Donnelly from the bench with a groin injury. He joined a long list of absentees ahead of kick-off.
Dylan Hill saw an early, angled effort deflect wide, while Rhys Lovett produced an excellent save to deny Yassine En-Neyah. Harvey's deflected effort subsequently rattled the crossbar for Truro, while Hill robbed ex-Pilgrim Sam Sanders but blasted over from the edge of the penalty area.
United failed to clear their Iines in the final minute of the first half, with PYKE stabbing the loose ball home amid a packed Boston box.
Matters got worse after the break when Greg Sloggett was adjudged to have fouled HARVEY, who picked himself up to sail home the spot-kick.
Truro killed off the contest six minutes later when DEAN swooped to lash the ball home, after the Pilgrims had once again failed to clear the danger.
Truro (3-1-4-2): Aidan Stone; Christian Oxlade-Chamberlain, Will Dean, Sam Sanders; Dan Rooney; Zac Bell, Yassine En-Neyah, Jake Taylor (Lirak Hasani 64), Ryan Law; Tyler Harvey, Rekeil Pyke (Dominic Johnson-Fisher 70). Subs (not used): Connor Riley-Lowe, Luke Jephcott, Ben Starkie, Shaun Donnellan, Dan Lavercombe (gk).
Boston (3-4-2-1): Rhys Lovett; Connor Teale, Tommy Fogarty (Jacob Scott 78), Alex Lankshear; Ben Grist, Jordan Richards, Greg Sloggett, Michael Kelly (Rocco Coyle 72); Dylan Hill, Arjan Raikhy (Jordy Hiwula 46); Lenell John-Lewis (Manni Norkett 72). Subs (not used): Luca Alonzi, Bobby Jones (gk).
Referee: Niall Smith.
Attendance: 2,116 (196 visitors).
PIC: Chris Bray.