Allen got off to a great start, punishing Wilson for missing a simple red to take the first frame with a break of 99.
The Englishman hit back however, with a break of 63 to level matters and the pair traded the next two frames as well to head into the interval all square.
Champion of Champions
O'Sullivan clinches title with century in final-frame shootout
11/11/2018 AT 14:17
Wilson then went to 5-3 ahead, after a break of 125 in the eighth frame and seemed assured of the win. However, the Northern Irishman hit back to take the match to a decider.
Allen, who lost to the Antrim player in the Masters final in January, recovered his composure, however, to build a break of 89 which was good enough to take the match.
He will now face O'Sullivan, who beat Shaun Murphy 6-3 in the other semi-final, in the showpiece event on Sunday.
Champion of Champions
O’Sullivan ousts Murphy to make Champion of Champions final
09/11/2018 AT 22:07
Champion of Champions
Mark Allen hits three centuries to reach semi-finals
08/11/2018 AT 16:30