He was honoured for the soundtrack to EO, a feature film by veteran director Jerzy Skolimowski that is the Polish candidate for an Academy Award.
EO is the name of a nomadic grey donkey which, after being removed from a travelling circus, begins a trek across the Polish and Italian countryside, experiencing cruelty and kindness in equal measure.
Born in 1971, Mykietyn is a graduate of the Music Academy in Warsaw.
In addition to a wide-ranging output of symphonic, chamber and vocal music, he has made a name for himself in theatre and films. He has written soundtracks for films by directors such as Andrzej Wajda and Małgorzata Szumowska.
The winners of the Excellence Awards in cinematography, design, editing, sound and music were unveiled on Wednesday.
The winners in the remaining categories will receive their awards at the European Film Awards ceremony on December 10 in Reykjavík.
Skolimowski is one of five filmmakers shortlisted in the European Director category.