On May 21, 2005, Fedek was ordained to the priesthood for the Archdiocese of Chicago at
Holy Name Cathedral in Chicago by Cardinal
Francis Eugene George.After his ordination, the archdiocese assigned Fedek as an associate pastor at Saint Mary of the Annunciation Parish in Mundelein. He was named assistant vocation director for Vicariate I in 2007. Fedek was transferred in 2010 to serve as pastor of Our Lady of Victory Parish in Chicago. Fedek was named as coordinator of the Polish Ministry Council in 2015 and in 2017 was reassigned as pastor of Immaculate Conception Parish in Chicago. In 2020, Cardinal
Blase Cupich named Fedek as his administrative secretary. ==Auxiliary Bishop of Chicago==