Lauridsen was born February 27, 1943, in Colfax, Washington in a family of migrants from Denmark. He was raised in Portland, Oregon, where his mother worked as a bookkeeper and his father was with the United States Forest Service. His mother was a pianist who had played in her high school dance band, and Lauridsen developed a love for music at an early age, by listening to her play swing jazz and singing to him. At age eight he started playing the piano, and a couple of years later learned to play the trumpet. He studied composition with Ingolf Dahl, Halsey Stevens, Robert Linn, and Harold Owen at the University of Southern California in the 1960s.
Lauridsen's vocal compositions, including seven vocal cycles and a series of sacred a cappella motets, are featured regularly in concerts worldwide. In particular, O Magnum Mysterium, Dirait-on (from Les Chansons des Roses) and O Nata Lux (from Lux Aeterna) have become popular items in the choral repertoire.
The musicologist and conductor Nick Strimple, in discussing Lauridsen's sacred music, described him as "the only American composer in history who can be called a mystic, (whose) probing, serene work contains an elusive and indefinable ingredient which leaves the impression that all the questions have been answered ... From 1993 Lauridsen's music rapidly increased in international popularity, and by century's end he had eclipsed Randall Thompson as the most frequently performed American choral composer."
Lauridsen's works have been recorded on over 100 CDs, three of which have received Grammy nominations. His principal publishers are Peermusic (New York/Hamburg) and Peer's affiliate, Faber Music (London).
A recipient of numerous grants, prizes and commissions, Lauridsen chaired the Composition department at the USC Thornton School of Music from 1990–2002, founded the School's Advanced Studies Program in Film Scoring, and is currently Distinguished Professor of Composition.
In 2006, Morten Lauridsen was named an "American Choral Master" by the National Endowment for the Arts. In 2007, he received the National Medal of Arts from the President of the United States in a White House ceremony, "for his composition of radiant choral works combining musical beauty, power and spiritual depth that have thrilled audiences worldwide."