Gate took the lead but bowed out of the Lancashire Challenge Trophy against the holders and 17-time winners from Vanarama National North.
The hosts held their own in the early stages of this second-round tie against a side who play three levels above them, though it took a last-ditch tackle by Mike Hall to deny a clear scoring chance.
Chorley were having the majority of possession and should have scored after 13 minutes, when striker Marcus Carver was left with his head in his hands after slicing a shot wide.
Chorley had a penalty appeal turned down as the first half ended goalless.
Jamie Gibson sparked life into Gate with a mazy run on the hour and they took the lead six minutes later, when Ryan Riley powered his header past keeper Adam Caunce from a Joe Noblet corner.
Chorley hit back almost immediately after the restart, when defender Daniel Cowan scrambled the ball in after Gate failed to clear their lines.
And the winner followed on 79 minutes, when Adam Roscoe smashed home a corner at the back post.
Gate return to league action at home to Hanley Town on Saturday.
Gate: Fletcher, Stayte, B.Seear, Alexander, Rossall, Hall, Penswick, Gibson, Noblet, Dawson , Riley. Subs: Richards, Carroll, Bamba, R.Seear, Tanser.