Isang Yun was born 17 September 1917, near the harbour city Tong Yong, in South Korea. He moved to Berlin in 1964. From 1933 to 1944, he studied music in Korea and Japan. He was active in the struggle for Korean independence, and, as a resistor of the Japanese occupation, he lived in hiding before being arrested and made a political prisoner.

From 1945 to 1956, he undertook social work, directed an orphanage, and was a music teacher as well as a lecturer at Seoul University. He received the South Korean Prize for Culture in 1955. He studied in Paris and Berlin from 1956 to 1959, with, among others, Boris Blacher and Josef Rufer. He also participated in the Darmstadt Summer Course.

In 1967, he was kidnapped in Berlin by the South Korean Secret Service and held as a prisoner under the Park regime. He was freed in 1969 when the regime gave in to protests and international condemnation of his incarceration.

He went on to teach composition at the Hanover Conservatory from 1969 to 1970, and at the Berlin Hochschule from 1970 to 1985. Having become a German citizen in 1971, he once again became politically active, participating in protests with fellow Koreans in exile in the United States and Japan who were demanding democracy and the reunification of the two countries.

Yun was a member of the Fine Arts Academies of Hamburg and Berlin, and received an honourary doctorate from Tübingen University in 1985.

He died 3 November 1995 in his adopted homeland.