Orrego Salas was born in Santiago, Chile. He began his studies in composition in his native country with Pedro Humberto Allende and Domingo Santa Cruz. His music came to the attention of American composer Aaron Copland with whom he subsequently studied at Tanglewood in 1946 along with a group of Latin American composers that also included Roque Cordero, Alberto Ginastera, Julián Orbón and Héctor Tosar. While in the United States (1944–46), he additionally studied composition with Randall Thompson and musicology with Paul Henry Lang on a Guggenheim Fellowship. A second Guggenheim brought him back to the United States in the early 1950s. Throughout that decade, works of his were performed by the Juilliard Quartet, the Louisville Orchestra, and the National Symphony Orchestra. In 1961, he permanently relocated to the United States to work at Indiana University, where he co-founded the Latin American Music Center. In 1992 he received Chile's National Prize for Musical Arts.
He has been one of the foremost Chilean composers and one of the most widely known of the musicians from that country around the world. Highlights from his catalogue include six symphonies, four string quartets, two piano concertos, a violin concerto, the cantata América, no en vano invocamos tu nombre (on texts by Pablo Neruda), the vocal works El Alba del Alhelí and Canciones Castellanas (which was performed during the ISCM World Music Days in 1949), and the piece Un Canto para Bolívar composed for Quilapayún, the most important ensemble of Nueva Canción Chilena.
- "Lanzan disco con música para saxofón compuesta por Juan Orrego Salas" [Album Released With Music for Saxophone Composed by Juan Orrego Salas]. El Mercurio (in Spanish). Santiago. 28 September 2004. Retrieved 12 December 2017.
- bio page from Indiana University, archive from 29 December 2010 at the Wayback Machine (archived December 29, 2010) (accessed 1 October 2013).
- La Ciudad Celeste, conducted by Carmen-Helena Téllez
- A conversation with Juan Orrego-Salas, recorded March 1, 2014
- Interview with Juan Orrego-Salas, August 17, 1991
- A Latin American Composer in the United States, 2004