[2] Internationally, he is best known for his genre scores, notably his music for mondo, giallo, horror, and Spaghetti Western films.

He studied at the Conservatorio Statale di Musica "Gioachino Rossini" in his hometown of Pesaro before moving to Rome in 1948 and finding work with the RAI orchestra.

One of his early film scores was for Paolo Cavara and Gualtiero Jacopetti's 1962 pseudo-documentary Mondo Cane, whose main title-song More earned him a Grammy and was also nominated for an Oscar as Best Song.

The success of the soundtrack of Mondo Cane led Ortolani to score films in England and the United States such as The Yellow Rolls-Royce (1964), The Spy with a Cold Nose (1966), The Biggest Bundle of Them All (1968) and Buona Sera, Mrs. Campbell (1968).

These include Il Sorpasso (1962), Castle of Blood (1964), Africa Addio (1966), Day of Anger (1967), Anzio (1968), The McKenzie Break (1970), The Hunting Party (1971), A Reason to Live, a Reason to Die (1972), Seven Blood-Stained Orchids (1972), The Fifth Musketeer (1979), From Hell to Victory (1979), the controversial Ruggero Deodato films Cannibal Holocaust (1980) and The House on the Edge of the Park (1980), and the first series of La piovra (1984).