Borca studied music at the University of Wisconsin with John Barrows and Arthur Weisberg, graduating in 1971. While at the University of Wisconsin, she met Cecil Taylor, who taught at the university during the 1970/1971 academic year. Borca studied with Taylor, played in his big bands, ensembles, and the Cecil Taylor Unit, and was his assistant while he worked in the Black Music Program at Antioch College in Yellow Springs, Ohio. She was an assistant to Taylor's longtime collaborator, saxophonist Jimmy Lyons, while he was artist-in-residence at Bennington College in Bennington, Vermont in 1974. Borca married Mr Lyons and played with his ensemble until he died in 1986. She has performed with her own bands in the U.S and Europe, including The Berlin Jazz Festival, The Vision Festival,Jazz Happening in Finland, The Taktlos Festival in Switzerland, The Vision Festival in NYC,The Newport Festival Salute to Women in Jazz and many other clubs, Concerts and venues. She was a featured artist in the international women’s orchestra of soloists and composers, Canaille, which performed at the Calouste Gulbenkian Art Foundation in Lisbon, Portugal. She is recorded with her band, CecilTaylor, Jimmy Lyons, Bill Dixon, William Parker, Paul Murphy and others.
She was an Artist-in-Residence at the Jyderup Accordeontrat in Denmark in Oct of 2016.
More recently on Oct.5, 2019 she performed her compositions/improvisations with her band, the Karen Borca Quartet at Jazz at Atlas in Newburgh, N.Y.. Also on Oct. 24th & 26th 2019, Karen Borca arranged and orchestrated the music of Cecil Taylor for the Karen Borca Big Band. She rehearsed the group and conducted a performance of Mr Taylor’s music with that group for the conference Unit Structures-The Art of Cecil Taylor in New York City.
On December 1st, 2020 Borca’s group, including William Parker, Hilliard Greene and Newman Taylor Baker, played a live stream video with Arts for Art celebrating the birthday of Jimmy Lyons.
Karen played with Willian Parker and NewmanTaylor Baker at a Riverside Park sculpture on Sept. 12,2021, presented by the Jazz Foundation of America. And, on Oct. 24, 2021, she performed with Hill Greene and Jackson Krall at St Mark’s Church , and later that day at the Catalytic Sound Festival with Fred Lomberg-Holm and Michael Wimberly, at the Fridman Gallary NYC.