Mist Thorkelsdóttir studied piano and harpsichord at the Reykjavík College of Music. In 1982, she received a B.A. degree from Hamline University, where she studied composition with Russel G. Harris. She continued composition studies with Lejaren Hiller and Morton Feldman at the State University of New York at Buffalo in 1983. She returned to Iceland, taught the piano for a few years, and took an active part in organisations such as “Musica Nova” and “Young Nordic Music”. In 1993 Mist Thorkelsdóttir received a MM degree from Boston University, where her principal teachers were Theodor Antoniou and Lukas Foss.
Her trio, Trinity, won 2nd prize in a contest for young composers sponsored by the Iceland State Radio in 1985. She has received commissions from individuals and institutions in Iceland, Sweden and the United States.
Her catalogue contains well over forty compositions: solo pieces, chamber music works, choral and orchestral compositions.
Mist Thorkelsdóttir teaches composition at the Reykjavík College of Music and takes an active part in group activities amongst Icelandic composer. She is currently the chairman of the Iceland Music Information Centre and is on board in the Icelandic Composer´s Society.