He was an early associate of Francis Ford Coppola and Roger Corman, and worked on many films distributed by American International Pictures (AIP) during the 1960s and 1970s.

Hill's best-known directorial works include Spider Baby (1967), Pit Stop (1969), The Big Doll House (1971), Coffy (1973), Foxy Brown (1974), and Switchblade Sisters (1975).

[7] His father, Roland Everett Hill (February 5, 1895 – November 10, 1986),[8] worked as a set designer and art director for First National Pictures and Warner Bros.[7] on films including The Jazz Singer, Captain Blood, Action in the North Atlantic, and Captain Horatio Hornblower, and as well was an architect who designed the centerpiece Sleeping Beauty Castle at Disneyland in California.

[10] He went on to postgraduate studies at UCLA Film School, where instructor and former movie director Dorothy Arzner encouraged Hill and his classmate and friend Francis Ford Coppola.

[10] His short The Host starred Sid Haig, an acting student at the Pasadena Playhouse under teacher Arzner, who introduced them;[10] this marked the first of several films together.

[4][11] Hill recalled in a 2000s interview that when he made The Host, I had been reading James Frazer ... and I had enjoyed his best-known book, The Golden Bough; in fact, my writing teacher said of 'The Host', “This is the story that Frazer forgot to tell.” It was influenced by his writing and if you see Apocalypse Now and look at the very last act of the movie, the camera explores Kurtz’s hideaway and you see a stack of books on his shelf.