Finch found Matt Uren — who was awarded the Dalt White Trophy as the Yates Cup MVP — seven times for 128 yards and two touchdowns. Receiver Brian Marshall had 43 yards and a touchdown.
Western kicker Liram Hajrullahu was perfect on four field-goal attempts, including one from 49 yards.
"Our whole team played awesome," Finch said. "My O-line bought me so much time and the receivers made some fantastic catches, so that's all you can ask for as a quarterback."
Gaels quarterback Billy McPhee was 21 for 35 for 275 yards with two touchdowns and two interceptions. Receivers Doug Corby and Justin Chapdelaine each had 82 yards and a touchdown.
Queen's was 7-1 in the OUA regular season with it's only loss coming against the Mustangs at TD Waterhouse Stadium. Western is undefeated.
"Our goal was to get to the Yates Cup game, many of the kids would have been disappointed had we not got here," said Queen's head coach Pat Sheahan. "We did get here and we competed for a championship. Sometimes you have to win some big games on the road and these were the two we couldn't win against the best team."
The No. 4 Gaels put up a 5-3 lead after the first quarter, but the Mustangs exploded for 45 straight points to put the game out of reach.
Queen's sparked its offence in the fourth quarter as McPhee hooked up with Chapdelaine for a score and two-point conversion to bring the game to 51-21. The Gaels added a rouge for the final score.
The Gaels' Justin Baronaitis led all defensive players on the day with 13.5 tackles while Western's Preston Huggins had eight tackles and an interception.
The victory marks Western head coach Greg Marshall's 18th Yates Cup. Marshall has hoisted the trophy four times as head coach of the Mustangs, four times as head coach at McMaster, seven times as a Mustangs assistant coach and three times as a Western player.
Western travels to McMahon Stadium in Calgary to take on the Hardy Cup champion Dinos for the CIS Mitchell Bowl next Saturday.
DINOS 43 BISONS 28
At Calgary, running back Mercer Timmins rushed for 279 yards and two touchdowns to lead Calgary to its sixth consecutive Hardy Cup with a convincing win over Manitoba. Quarterback Andrew Buckley had 262 passing yards and two touchdowns in the Canada West final.
MOUNTIES 20 HUSKIES 17
At Halifax, receiver Josh Blanchard had 71 yards and a touchdown and quarterback Brandon Leyh threw for 245 yards to lead Mount Allison past Saint Mary's in the AUS championship Loney Bowl. The Mounties will play Laval next week in the Uteck Bowl.
ROUGE ET OR 14 CARABINS 11
At Laval, Que., Boris Bede kicked a 25-yard field goal and the Rouge et Or scored four team safeties to slip past the Montreal Carabins and win the Dunsmore Cup, the RSEQ championship. Manuel Crisi-L. rushed in a 10-yard touchdown for Montreal.