His growing interest in theater put an end to his original plan to be an engineer, and he gained experience in radio at the university's station, WHA.

[2] Waterman began his radio career at WIBA in Madison, singing in a quartet that performed "musical interludes between programs,"[2] and came to NBC in Chicago in early 1936.

[citation needed] At the same time he was heard as Gildersleeve, Waterman had a recurring role as Mr. Merriweather in the short-lived but respected radio comedy vehicle for Ronald Colman and his wife Benita Hume, The Halls of Ivy.

Waterman's pre-Gildersleeve radio career, in addition to Tom Mix, had included at least one starring vehicle, a short-lived situation comedy, Those Websters,[4] that premiered in 1945.

He had radio roles between the mid-1930s and 1950 on such shows as Chicago Theater of the Air (variety) and Harold Teen (comedy), plus four soap operas: Girl Alone,[5] The Guiding Light, Lonely Women,[6] The Road of Life and Kay Fairchild, Stepmother.

One obituary noted, "He was believed to be the only person to have served as a member of the union's board of directors in four different locales: Chicago, Los Angeles, San Francisco and New York.