Luke Conlan’s double either side of the break - added to by second half goals from Danny Whitehead and Siyabonga Ligendza - sealed the deal for Adam Murray’s Coasters.
Sam McLintock had reduced the arrears briefly at one stage - but United never looked like mounting a serious comeback.
Chances were few and far between during a tight first half, but it was the hosts who took the lead in the 35th minute when CONLAN struck at the second attempt, having seen Sam Long make a brilliant initial save, following Whitehead's cross from the right.
Boston's best chance of the half fell to Jake Wright, who blazed over from close-range after meeting McLintock's inviting ball from the left.
Fylde started the second half in red-hot fashion, with Long required to save from Ligendza and Luke Burke within 30 seconds of the restart.
They did add their second goal in the 53rd minute when WHITEHEAD rolled the ball home after Nick Haughton had seen a low effort blocked.
The Pilgrims gave themselves help when substitute Jordon Crawford delivered from the right-hand side and McLINTOCK swept the ball home from close-range.
United's hopes of a sustained comeback were extinguished with 17 minutes to play when CONLAN fired home his second of the night, after Whitehead had miscued his own effort in front of goal.
Fylde wrapped up the points in the 83rd minute when the post denied Conlan a hat-trick, with LIGENDZA bagging the rebound.
AFC Fylde (3-4-2-1): Chris Neal; Luke Burke (Emeka Obi 86), Alex Whitmore, Pierce Bird; Connor Barrett (Will Hatfield 79), Curtis Weston, Danny Philliskirk, Luke Conlan; Danny Whitehead, Nick Haughton (Joe Rowley 86); Siyabonga Ligendza. Subs (not used): Jordan Cranston, Keenan Patten.
Boston (4-2-2-2): Sam Long; Keenan Ferguson, Jo Cummings, Ben Pollock, Tom Nixon; Tom Platt, Lebrun Mbeka; Scott Pollock (Will Atkinson 70), Sam McLintock; Jake Wright, Jaanai Gordon (Jordon Crawford 55). Subs (not used): Alex Brown, Tom Solanke, Rhys Davies (gk).
Referee: Helen Conley.
Attendance: 684.
PIC: Steve McLellan.