Mathers began his career at the age of two when he appeared as a child model for a department store ad.Soon after, he starred in a commercial for PET Milk opposite vaudeville comedian Ed Wynn.

His early movies included This Is My Love (1954), Men of the Fighting Lady (1954), The Seven Little Foys (1955) and Alfred Hitchcock‘s black comedy The Trouble with Harry (1955), in which he plays Arnie, the son of Shirley MacLaine‘s character, and finds Harry’s body in the nearby forest.

Mathers states that he got the role of Beaver Cleaver after telling the show’s producers he would rather be at his Cub Scout meeting than to do an audition for the part. The producers found his candor appealing and perfect for the role. Mathers played the Beaver for six years, appearing in all 234 episodes of the series. He was the first child actor to have had a deal made on his behalf to get a percentage of the merchandising revenue from a television show. Leave It to Beaver still generates revenue more than six decades after its original production run.