His most successful and, arguably, most identifiable role came in 1952, when he joined the Broadway production of "The Seven Year Itch" as protagonist Richard Sherman. With Vanessa Brown as "The Girl", Ewell played the part more than 950 times over three years, as he indicated in a mystery guest appearance on the June 12, 1955 airing of "What's My Line?" to promote the 1955 film adaptation. He earned both the Tony Award for Best Actor in a Play and the Golden Globe Award for Best Actor – Motion Picture Musical or Comedy for portraying Sherman.