Heineman was designated for assignment by the Blue Jays on Friday, when Alejandro Kirk made his return from the injured list.
The 34-year-old catcher had struggled at the plate through 33 games this season, carrying a .154 average and .410 OPS.
Despite being unable to get much going offensively, Heineman performed as one of the best defensive catchers in baseball, ranking third among all qualified backstops with a plus-7 fielding run value.
In 2025, Heineman hit .289 with three home runs and a .777 OPS in 64 games, helping the Blue Jays win a division title.
An eighth-round pick of the Houston Astros in 2012, Heineman has spent three different stints with the Toronto organization (2022, 2023 and 2024 to 2026).