He studied with Ernst Krenek from 1936-1947: "I had already studied—and abandoned—the twelve tone system before most other Americans had taken it up." He influenced notable students Morton Subotnick, Pauline Oliveros, Terry Riley, and Paul Dresher. He is also the author of The Structure of Music: A Listener's Guide, which he claimed helped him overcome a "contrapuntal obsession", and Sound Structure in Music (1975), an important early attempt to systematically study timbre in music.
He taught at the College of St. Catherine in St. Paul, Minnesota, San Francisco State College, the University of California, Berkeley, and the San Francisco Conservatory. With composer Wilbur Ogdon, he founded the music department at the University of California, San Diego in 1967: "We decided we wanted a department where composers could feel at home, the way scholars feel at home in other schools." While there he met faculty performers such as bassist Bertram Turetzky, trumpeter Edwin Harkins, flutist Bernhard Batschelet, and singer Carol Plantamura: "I could go to Bert, or Ed, with something I'd written down and ask 'Hey, can you do this?' And I'd get an immediate answer. It was a fabulous time for cross-feeding." He also helped start the San Francisco Tape Music Center. Pauline Oliveros, among others, praises his teaching:
Robert Erickson was my principal composition teacher from 1954-60 and my professional mentor. His teaching was notable for supporting me to work in my own way as he did with all his students. His attitude in teaching composition was devoid of sexism or racism. He was ethical. His delight was helping others to be creative and professional in composition what ever [sic] the style. Erickson was skillful in drawing out the best abilities of his students. He was tireless in his investigation of music and had a wealth of advice and pointers to relevant musical resources—always useful and specific. His guidance was invaluable to me and to my peers (all male). None of us sounded alike in our compositions even though we liked and admired each other's work.
Erickson was one of the first American composers to create tape music: "If you get right down to the bottom of what composers do, I think that what composers do now and have always done is to compose their environment in some sense. So I get a special little lift about working with environmental sounds." He also has used invented instruments such as stroking rods, used in Taffy Time, Cardinitas 68, and Roddy (electronic tape composition), tube drums, used in Cradle, Cradle II, and Tube Drum Studies, and the Percussion Loops Console designed with Ron George, used in Percussion Loops.
Many UCSD faculty performers appear on his 1991 CRI release Robert Erickson: Sierra & Other Works (CD 616), playing works written for and with them:
- Kryl (1977), Harkins, named after the travelling cornet player Bohumir Kryl. The piece from time to time creates a hocket between the singing and playing.
- Ricercar À 3 (1967), Turetzky. For bass soloist live and on two tape tracks.
- Postcards (1981), Plantamura and lutenist Jürgen Hübscher
- Dunbar's Delight (1985), timpanist Dan Dunbar. Virtuoso solo piece for timpani.
- Quoq (1978), flutist John Fonville. Named after "Finnegans Wake".
- Sierra (1984), baritone Philip Larson, SONOR Ensemble conducted by Thomas Nee. Commissioned by Thomas Buckner.
He also has an album Pacific Sirens on New World Records.
He received several Yaddo Fellowships in the fifties and sixties, a Guggenheim Fellowship in 1966, a Ford Foundation Fellowship, was elected as a Fellow of the Institute for Creative Arts of the University of California in 1968, and his string quartet Solstice won the 1985 Friedham Award for Chamber Music. There are two books about Erickson's life and music: Thinking Sound Music: The Life and Work of Robert Erickson by Charles Shere and Music of Many Means: Sketches and Essays on the Music of Robert Erickson by Robert Erickson and John MacKay.
He suffered from a wasting muscle disease, polymyositis, and was bedridden and pained for fifteen years before his death, though his final work was Music for Trumpet, Strings, and Tympani (1990).
- American Classics - A Continuum Portrait Vol 9 - Erickson: Recent Impressions, Songs, High Flyer, Summer Music. Naxos 8.559283
- Robert Erickson: Pacific Sirens. New World Records 80603
- Robert Erickson: Kryl, Ricercar, Postcards, Dunbars Delight. CRI 616
- Robert Erickson: Auroras. New World Records 80682
- Robert Erickson: Complete String Quartets. New World Records 80753
- Robert Erickson: Duo, Fives, Quintet, Trio. New World Records 80808
- Erickson, Robert. 1975. Sound Structure in Music. Berkeley and Los Angeles: University of California Press. ISBN 0-520-02376-5.
- Erickson, Robert. 1988. "Composing Music". Perspectives of New Music 26, no. 2 (Summer): 86–95.
- Erickson, Robert. 1991. Sierra & Other Works. CRI CD 616. Liner notes by Alan Rich, Music Critic, L.A. Daily News.
- Erickson, Robert, and John MacKay. 1995. Music of Many Means: Sketches and Essays on the Music of Robert Erickson. Lanham, Maryland: Scarecrow Press. ISBN 0-8108-3014-0
- MacKay, John. 1988. "On the Music of Robert Erickson: A Survey and Some Selected Analyses". Perspectives of New Music 26, no. 2 (Summer): 56–85.
- Oliveros, Pauline. 1995. "A Former UCSD Professor Speaks Up: An Email Exchange" Fall 1995 - International Alliance for Women in Music (IAWM list). 
- Reynolds, Roger. 1988. "Wonderful Times". Perspectives of New Music 26, no. 2 (Summer): 44–55.
- Shere, Charles. 1995. Thinking Sound Music: The Life and Work of Robert Erickson. Berkeley: Fallen Leaf Press. ISBN 0-914913-33-6
- Shere, Robert. 2001. "Erickson, Robert". The New Grove Dictionary of Music and Musicians, ed. S. Sadie and J. Tyrrell. London: Macmillan.
- Erickson, Robert. Quoted in Robert Erickson: Sierra & Other Works (1991 CRI CD 616). Liner notes by Alan Rich, Music Critic, L.A. Daily News.
- Oliveros, Pauline. "A Former UCSD Professor Speaks Up: An Email Exchange" Archived 2004-08-16 at the Wayback Machine Fall 1995 - International Alliance for Women in Music (IAWM list).
- University of Akron Bierce Library Smith Archives Composer Profile: Robert Erickson
- ClassicToday.com Review of Pacific Sirens by Robert Erickson Artistic quality: 8, Sound quality: 9.
- Dunbar's Delight Review of Sierra & Other Works by Elliott Schwartz, American Music, Fall, 1998
- AllMusic "Robert Erickson" biography by Joslyn Layne
- Interview with Robert Erickson, February 27, 1988
- Robert Erickson Papers MSS 96. Special Collections & Archives, UC San Diego Library.