Jacobs, from Sault Ste. Marie, Ont, trailed 3-1 after four ends but grabbed a deuce in the fifth and then scored a single in the eighth to complete the come-from-behind win.
As the men's points leader for the Grand Slam season, Jacobs takes home $75,000 in bonus winnings in addition to $24,500 for the Players' Championship crown.
"It was a fantastic curling season for us. This is the best we've ever played on the cashspiel circuit," said Jacobs. "I'm really proud of the way we played throughout the World Curling events this year and throughout the Grand Slam series. To pick up this last win is just huge for us."
McEwen, from Winnipeg, was the only player to go undefeated leading up to the championship at 5-0 while Jacobs went 4-1 — his only loss coming against Winnipeg's Reid Carruthers in round-robin play.
Jacobs topped Edmonton's Brendan Bottcher 6-5 earlier in the day to qualify for the finals while McEwen beat Toronto's John Epping 7-3 in the other men's semifinal.
On the women's side, singles in both the seventh and eighth ends gave Scotland's Eve Muirhead a 4-2 win over Russia's Anna Sidorova in the final Grand Slam Curling competition of the season.
Muirhead takes home $23,500 for the Players' Championship win and an additional $35,000 in bonus winnings for being the women's leader in Grand Slam points for the season.
"It's a great feeling. We love playing these Grand Slam events — they're massive. To win the overall bonus makes it even better," said Muirhead. "It's been a tough week. All of these games have been so tough but we really pulled together well as a team. To come out on top, we couldn't have asked for more."
Sidorova opened the scoring with a single in the second end before Muirhead tied it in the third.
The two sides again traded points in the fourth and fifth ends before Muirhead broke the 2-2 tie in the seventh.
Muirhead edged Ottawa's Rachel Homan 8-7 in the semifinal earlier in the day. Sidorova beat Edmonton's Val Sweeting 5-3 to book her spot in the women's championship.
A combined purse of $200,000 was awarded to the 24 men's and women's teams competing in the six day tournament, which was held at Ryerson's Mattamy Athletic Centre.