Encarnacion extended his hitting streak to 24 games with a three-run blast off Detroit Tigers pitcher Buck Farmer in the first, drilled a two-run shot off Guido Knudson in the sixth and connected off Alex Wilson in the seventh. Encarnacion tied a Blue Jays record with nine RBIs.
"He's some kind of locked in," manager John Gibbons said.
The Blue Jays' 15-1 win was paused briefly after the grand slam as dozens of fans tossed caps into the outfield to honor Encarnacion's homer hat trick. It was his third slam of the season, matching the club record shared by Carlos Delgado and Darrin Fletcher.
Encarnacion said he wasn't familiar with the hockey-style tribute until a teammate filled him in.
"[Catcher Dioner] Navarro told me after they throw all the hats to the field, he told me when they score three goals, they do that," Encarnacion said. "It made me feel happy."
Gibbons was also a little confused at first when the hats started flying.
"I hadn't seen it before," Gibbons said. "Don't they normally throw octopus or something?"
Staff collected the hats and put them in a bag for Encarnacion, who posed for a photo with his haul and posted it to Instagram.
"I'm maybe going to sign them and give them back to their owners for appreciation for throwing them on the field," he said.
Encarnacion was left on deck for the final out in the eighth, costing him a chance to match the major league mark for home runs in a game.
His hitting streak is the longest in the majors this season and the longest since Colorado's Nolan Arenado had a 28-game run in 2014.The Toronto slugger is batting 36-for-90 (.400) with 10 homers and 34 RBIs over the streak. He needs to keep the streak going five more games to break the franchise record of 28 games set by Shawn Green in 1999.
This was Encarnacion's fourth multihomer game this year and the 21st of his career. He finished 3-for-5, scored four times and boosted his season totals to 29 homers and 90 RBIs.
Roy Howell was the last Blue Jays player with nine RBIs in a game, doing it against the New York Yankees on Sept. 10, 1977, in Toronto's debut season.
The Associated Press and ESPN Stats & Information contributed to this report.