He founded the film production company Filmways, Inc. in 1960 and remained with the company until 1972. Filmways started making TV commercials, moved into documentaries then sitcoms; by 1963 Filmways were making $13 million a year. In 1972 he became an independent producer.
He attempted to "create" female movie stars during the 1960s; the actresses who achieved the greatest success under his tutelage were Ann-Margret, Tuesday Weld and Sharon Tate, who featured in several of his films from 1964 until her death in 1969. He is a cousin of neurosurgeon Joseph Ransohoff.