The deal will pay McCarron $700,000 at the NHL level and $125,000 in the AHL with a guaranteed salary of $150,000.
McCarron, 24, spent the 2018-19 campaign with the AHL's Laval Rocket, recording seven goals and 21 points in 32 games with the Habs' minor-league affiliate.
A native of Grosse Pointe, MI, McCarron has appeared in 69 career NHL games with the Canadiens, scoring two goals and collecting eight points.
The 6-foot-6, 230-pound American was Montreal's first-round selection (25th overall) in 2013.