Gate extended their unbeaten run in the Hallmark Security League to 10 games and completed a double over the relegated bottom club.
READ MORE: Squires Gate 1 Hanley Town 0
Gary Pett went close after only five minutes but his clever flick from Andrew Richards’ cross was saved.
Ryan Charnley was the next to take aim when he cut inside after 11 minutes but his shot was deflected wide for a corner.
Gate opened the scoring after 31 minutes, when the in-form Pett slotted past the keeper as the visitors appealed in vain for offside.
Dean Ing was the matchwinner in the teams’ previous encounter but he shot over as Gate ended the first half 1-0 up.
Pett headed home at the back post nine minutes after the restart but this time was flagged offside.
Gate did double their lead on 61 minutes, when winger Ryan Riley showed great composure to chip the keeper for his first goal since returning to the club.
Max Rothwell, scorer of the only goal as Gate beat Hanley Town on Saturday, clipped the bar as he let rip from outside the box.
Jordan Salthouse was denied three times by the Darwen keeper but fellow substitute Connor Finlayson did get on the scoresheet after 79 minutes, tapping home his second goal for the club after the keeper spilled Scott Harries’ shot.
Finlayson then cut the ball back for Riley to score his second and Gate’s fourth with nine minutes remaining.
Gate remain ninth in the premier division with four to play and travel to Northwich Victoria on Saturday.
Gate: Fletcher, Mullen, Bamba, Colquhoun, Richards, Charnley, Ing, Rothwell, Riley, Harries, Pett. Subs: Hargreaves, Salthouse, Finalyson, Gray.