the son of a canadian father, mat clark was born in lakewood, colorado, before he moved to ontario with his family when he was four. prior to turning professional, clark played major junior hockey in the ontario hockey league with the brampton battalion. after two seasons with the battalion, and showing potential as a physical defensive defenseman by being selected as the best body checker and defensive defenseman in the eastern conference poll he was signed to a three-year entry-level contract with the anaheim ducks on march 31, 2010. he immediately made his professional debut at the end of the 2009–10 season with affiliate, the manitoba moose against the peoria rivermen on april 10, 2010.