His work is extensive and varied, including musical arrangement for theatre and many scores for television and film. In the 1970s he began a long association with Richard O'Brien. Hartley was originally part of the four-piece band for the The Rocky Horror Show. He went on to arrange the score for the London Stage show. He then went on to provide arrangements for the film adaptation, The Rocky Horror Picture Show (1975) and its follow-up Shock Treatment (1981), and worked with O'Brien on another, as yet unproduced, sequel, Revenge of the Old Queen. His other 1970s film scores included The Romantic Englishwoman (1975), Aces High (1976), and the remake of The Lady Vanishes (1979).
In the 1980s, Hartley worked primarily in television, including providing the music for the 1986 Doctor Who story Mindwarp. However he also composed for film, including the Nicolas Roeg film Bad Timing (1980), Bad Blood (1982), The Trout (1982), The Return of Captain Invincible (1983), Sheena (1984) (for which Hartley was nominated for a Golden Raspberry Award), Dance with a Stranger (1985), The Good Father (1985), and Consuming Passions (1988). However, one of his lesser known works is the music for The Fifth Dimension, a dark ride at Chessington World of Adventures.
In the 1990s he provided the scores for many films including Afraid of the Dark (1991), The Secret Rapture (1993), Princess Caraboo (1994), Victory (1995), An Awfully Big Adventure (1995, which was released on CD), Rogue Trader (1999), and Alice in Wonderland (1999), in which he won an Emmy Award for Outstanding Music Composition for a Miniseries or a Movie (Dramatic Underscore).
- Dionysius 73 (Harrowgate Opera House, 1973) – composer, musical director
- The Threepenny Opera (Sydney Opera House, 1973) – musical arrangements
- The Rocky Horror Show (Royal Court Theatre, 1973) – musical director
- Tooth of Crime (Royal Court Theatre, 1974) – musical director
- T. Zee (Royal Court Theatre, 1976) – composer, musical director
- The Rocky Horror Show (Broadway, 1975) – vocal and dance music arrangements
- Disaster (Institute of Contemporary Arts, 1978) – composer, musical director
- The Stripper (Sydney Theatre Company, 1982) – composer, musical director
- The Rocky Horror Show (London, 1990) – musical arrangements
- The Stripper (UK tour, 2009) – composer, musical director
- "Richard Hartley". BFI.
- "Richard Hartley". richardhartley.net.
- "Richard Hartley - Movies and Filmography - AllMovie". AllMovie.