McDonald was born in Scranton, Pennsylvania and raised in Romulus, New York. He graduated from Ithaca College. He also studied at the Royal Academy of Dramatic Art in London, and was a member of the Actors Studio.
In addition to Steel Peel, his Broadway credits included the roles of C.K. Dexter Haven in High Society (opposite Melissa Errico) and Sam Carmichael in Mamma Mia! McDonald also starred in the national tour of Contact, and he wrote, directed, and starred in the solo show Chesterfield at the John Drew Theatre in East Hampton.
He appeared in such films as The Falcon and the Snowman and The Ice Storm; his numerous television credits include All My Children, Murder, She Wrote, Law & Order, and Sex and the City.
McDonald is survived by his wife, Mujah; their two children, Fosco and Ondino; his parents, James and Patricia; and his five siblings, including the actor Christopher McDonald. Funeral services will be held at 10am on Saturday, February 24 at the Cathedral of St. John the Divine. In lieu of flowers, the family asks that donations be made to the cancer charity Team Continuum.