Willem Jeths (Amersfoort, 1959) studied music in education at the Sweelinck Conservatorium in Amsterdam from 1980-1982. He then studied composition at the Utrecht Conservatory with Hans Kox and Tristan Keuris and Musicology at the Universiteit van Amsterdam. He completed his studies with a thesis on the composer Elisabeth Kuyper (1877-1953), which was published in the book Zes vrouwelijke componisten (Six female composers).
Willem Jeths has written chamber music, orchestral music, including solo concertos, songs and an opera, at first in an atonal idiom, later leaning toward a more traditional tonality. Many of his works have won prizes. In 1988 he won the Composition Prize of the Utrecht Conservatory. His work Novelette for violin and piano (1986) was selected to be performed at the ISCM World Music Days in Oslo, 1990. At the Carl-Maria-von-Weber-Wettbewerb für Streichquartettkompositionen in Dresden in 1991 he received an award for Arcate (1990) for string quartet. A year later this work, now in a version for string orchestra, won an award from the Music for String Compositions Competition of the Oare String Orchestra in Kent. Listeners of the Dutch classical radio broadcasting company Concertzender awarded Novelette second prize in a competition celebrating the 80th anniversary of BUMA in 1993. In 1996 he won second and third prize at the Internationaler Wiener Kompositionswettbewerbwith his violin concerto Glenz (1993) and his piano concerto.
In the 2004-2005 season he was composer-in-residence with Het Gelders Orkest and in 2006-2007 with the Orkest van het Oosten. In 2000 a three-day Willem Jeths Festival took place in Rotterdam.
Willem Jeths has been a teacher of composition at the Conservatorium van Amsterdam since 2007.