Kyriakos Sfetsas was born in Amfilochia in 1945. He was raised in the island of Lefkada where at an early age, he studied music at the Philarmonic Band and the National Conservatory. Then he studied piano at the National Conservatory of Athens with Krino Kalomiri and music theory with Michalis Vourtsis.

On 30th of August 1964 in Lefkada he accompanied Maria Callas on the piano, in her last performance in Greece. After the dictatorship in Greece (1967) he moved to Paris, where he studied with Max Deutsch, while seeking the mentorship and advice of Iannis Xenakis, Luigi Nono and Henri Dutilleux .

The first public performance of his work took place just after the uprising of May ’68 at the "Latin America Hall" in Paris. After that, his music was often performed and he had his first commissions (by French Radio and TV, the Ars Nova Orchestra and the Dance Group of Vitry) and then several of his works were performed in renowned international contemporary music festivals.

In 1974 he released for the first time one of his works on record: Four-channel electro-acoustic music for the Ballet Smog, one of the first pieces written for four-channel tape in the world. In 1975 he returned to Greece. He worked at the Third Programme of the Hellenic Radio and from 1982 to 1994 he served as head of the programme.
In 1980 he released the album "Choris Synora" with the Greek Fusion Orchestra.

His body of work consists of a large volume of composition (symphonic, choral, ballet and theatre music, chamber, electronic, pieces for solo instruments, pieces in jazz and fusion style, songs on Greek and world poems, music for films) and has been performed in many countries.

Since 1999 he lives and works in Lefkada.