Preves attended the University of Chicago. In 1931, he joined the Little Symphony — a Chicago Symphony training ground—and was promoted to the Chicago Symphony Orchestra in 1934. He became principal violist in 1939, which position he held until he retired from the Chicago Symphony Orchestra in 1986. He played under the batons of all the Chicago Symphony's conductors, up until Sir Georg Solti, except for the Chicago Symphony's founder, Theodore Thomas.
In 1963, he resigned as conductor of the Oak Park-River Forest orchestra, because
Carol Anderson, a talented black female violinist whom Preves had recruited for the symphony, was pressured to resign because of her race. The president of the orchestra quickly apologized, and urged Preves to continue to conduct the group. He did not return for 25 years and when he did, it was only to play as a soloist with the orchestra.
Ernest Bloch dedicated his Meditation and Processional to Milton Preves. Preves taught many students, some of whom continue to teach, passing down his style.