Husa was elected Associate Member of the Royal Belgian Academy of Arts and Sciences in 1974, and to the American Academy of Arts and Letters in 1994. He has received honorary doctorates from Coe College, the Cleveland Institute of Music, Ithaca College, Baldwin-Wallace College, St. Vincent College, and Hartwick College; and has been the recipient of many awards and recognitions, including a Guggenheim Fellowship and awards from the American Academy and Institute of Arts and Letters, UNESCO, the National Endowment for the Arts, the Koussevitzky Foundation, the Czech Academy for the Arts and Sciences, the Lili Boulanger Award, Bilthoven (Holland) Contemporary Music Prize, a Kennedy Center-Friedheim Award, and the Sudler International Award. His Concerto for Cello and Orchestra earned him the 1993 Grawemeyer Award. In 1995, Husa was awarded the Czech Republic's highest civilian recognition, the State Medal of Merit, First Class.

His String Quartet No. 3 received the 1969 Pulitzer Prize and, with over 7,000 performances, his Music for Prague 1968 has become part of the modern repertory. Another well-known work, Apotheosis of this Earth is called by Husa a "manifesto" against pollution and destruction. His works have been performed by major orchestras all over the world. Two works were commissioned by the New York Philharmonic: the Concerto for Orchestra premiered by Zubin Mehta, and the Concerto for Violin and Orchestra written for concertmaster Glen Dicterow and conducted by Kurt Masur; and the Concerto for Trumpet was commissioned by the Chicago Symphony Orchestra and Sir Georg Solti for performance in Chicago and on tour with principal trumpeter Adolph Herseth. Among his recent compositions are the String Quartet No. 4 (an NEA commission for the Colorado Quartet), Cayuga Lake (for Ithaca College's centennial celebration), and Les couleurs fauves for wind ensemble (written for Northwestern University).

Karel Husa has conducted many major orchestras including those in Paris, London, Hamburg, Brussels, Prague, Stockholm, Oslo, Zurich, Hong Kong, Singapore, New York, Boston, Washington, Cincinnati, Rochester, Buffalo, Syracuse, Louisville and others. Every year he visits the campuses of music schools and universities to guest conduct and lecture on his music.

Much of Husa's music is available on recordings issued by CBS Masterworks, Vox, Louisville, Phoenix, Crystal, CRI, Everest, Grenadilla, Sheffield, and other labels.