After five seasons in the minor leagues, Pompey made his MLB debut on September 2, 2014, becoming only the sixth player born in Ontario to play for the Blue Jays.

[4] He returned to Lansing in 2013 to play in 115 games, and finished the year batting .261 with six home runs, 40 RBI, and 38 stolen bases.

[8] Pompey was promoted to the Double-A New Hampshire Fisher Cats on June 27, 2014,[9] and to the Triple-A Buffalo Bisons on August 20.

[10] On August 26, the Blue Jays organization announced that Pompey would play for the Mesa Solar Sox of the Arizona Fall League at the completion of the 2014 season.

[11] He finished the 2014 minor league season with a .313 batting average, nine home runs, 52 RBI, and 43 stolen bases in 112 games played.

[1] After three additional appearances as a pinch-runner, Pompey had his first at-bat on September 10 against the Chicago Cubs and earned an RBI on a groundout to first base.

On September 19, Pompey recorded his first Major League hit, a single to right-field against New York Yankees starting pitcher Hiroki Kuroda.

[15] Pompey would hit his first career home run, a solo shot to right field, off Mariners ace Félix Hernández the following day.

[16] Playing against the Baltimore Orioles on September 26, Pompey had the best game of his young career, posting two runs scored and two RBI by hitting his first double and two triples, finishing the night 3–4.

[22] He appeared in 34 games for the Blue Jays in the 2015 regular season, and batted .223 with two home runs, six RBI, and five stolen bases.

[27] During the 2017 World Baseball Classic, Pompey suffered a concussion as he slid into second base during a play and was subsequently placed on the 60-day disabled list by the Blue Jays.

In a May 29, 2018 game for Buffalo, Pompey suffered a partial tear of the ulnar collateral ligament in his left thumb, sustaining the injury sliding headfirst into third base.

[38] Pompey split time in 2021 with the Double-A Rocket City Trash Pandas and the Triple-A Salt Lake Bees, hitting .276 with 5 home runs and 12 RBI.

His stint on the program was later commemorated by Great Lakes Brewery with a custom beverage called Electric Circus Tropical Pale Ale.