[citation needed] By the time he was 22, Roberts was successfully running his own independent public-relations counseling firm and was contributing comedy material to several Broadway musicals.

[1] In 1941, he collaborated with another young writer, Ivan Goff, on the theatrical suspense thriller Portrait in Black.

He briefly worked in films in the early 1940s, returned to the stage for six years, then settled in Hollywood permanently in 1949.

The pair contributed to the success of such varied projects as White Heat (1949), Captain Horatio Hornblower (1951), Shake Hands with the Devil (1959) and Midnight Lace (1960); and in 1957, they shared an Academy Award nomination for their scriptwork on Man of a Thousand Faces (1957).

Roberts and Ivan Goff were also executive producers for the weekly television series Mannix and Nero Wolfe.