Wilson edged home in an astonishing finale which included McGill missing a snooker eight times in succession and effectively concluded when Wilson fluked a green over three cushions.
The frame score finished 103-83 in favour of Wilson, who appeared to struggle to contain his emotions upon fluking the green, and subsequently broke down in a BBC interview.
Well done, @KyrenWilson!
It's not a dream #ilovesnooker @Betfred pic.twitter.com/uZMcrPmfa2— World Snooker Tour (@WeAreWST) August 14, 2020
Wilson had returned for their concluding session with a 13-11 advantage and stretched his lead to three frames with a nerveless break of 94.
But qualifier McGill stormed back with consecutive breaks of 84, 87 and 122 to achieve parity at the mid-session interval.
Wilson nudged back in front with a break of 82 but McGill appeared unfazed and pulled back level before a nerveless 98 sent him one frame from victory.
Wilson forced the decider after a re-rack, but neither player could possibly have envisaged the drama that was soon to unfold.
Both players missed simple chances to claim frame and match, with McGill running aground on 39 then Wilson missing a simple red to middle on 47.
How incredible is this final frame ???
My nerves are gone 😩😩😩 #wilsonmcgill #Snookerworldchampionships— Ken Doherty Official (@kendoherty1997) August 14, 2020
With the black teetering over the top pocket, Wilson snookered McGill on a nearby red and the Scot missed it eight times in a row – leaving him requiring snookers.
Yet Wilson duly stepped up and screwed the white back into the middle pocket, with another subsequent in-off handing his opponent back the initiative.
The red then became perched tight on the top lip of the middle pocket, with both players trying and failing to pot it via the bottom cushion.
McGill managed it at the second attempt but with the colours seemingly at his mercy he snookered himself on the green – which Wilson subsequently missed to effectively take the match.
After an extended safety battle, Wilson fluked the green via three cushions, leaving McGill requiring snookers again and Wilson ultimately thanking his outrageous fortune.
