Grean's first work was as a copyist in several big bands, including Glenn Miller, Artie Shaw, and Charlie Spivak.
In 1950, he wrote "The Thing," a popular song which reached number one on the charts in a version sung by Phil Harris.
One of Grean's compositions became a focus of litigation in 1958 in the case Dorchester Music v. National Broadcasting Company [171 F. Supp.
In 1969 he reached the charts as a performer, with his group, the Charles Randolph Grean Sounde, doing a version of Robert Cobert's "Quentin's Theme" from Dark Shadows.
(Billboard #13 pop, #3 easy listening, Cash Box #8, #5 RPM) In 1973, his group was the stage band for Jack Paar's return to late-night television, Jack Paar Tonite, which aired as one of the rotating programs featured on ABC's Wide World of Entertainment on the ABC television network.