The Clarksburg, West Virginia, native began his acting career on stage in the late 1940s in regional theatre productions in the Chicago area. His Broadway debut came in 1951 in the musical Make A Wish, followed by the Johnny Mercer musical Top Banana.
McKay is remembered best for his portrayal of Tony, originating the role in the 1958 West End premiere of West Side Story, with original Broadway cast member Chita Rivera. He also later starred in the original Tokyo production of West Side Story and in a 1964 revival at the City Center in New York.
McKay also appeared opposite Shirley Bassey in a 1959 London revival of Show Boat, and later co-starred with Elliot Gould in the 1963 London production of Leonard Bernstein’s On the Town. He also performed “Gotta Have Me Go With You” with Judy Garland, in 1954’s feature A Star Is Born, and in 1956 sang on Washington Square, an NBC variety series starring Ray Bolger.
McKay later moved to Connecticut, where he appeared in regional theatre productions and taught voice lessons, according to Playbill. He spent the last 20 years of his life in Manhattan.