He received his early education in local public schools, and entered St. Viator College at Bourbonnais, Illinois, in 1879, earning his bachelor's (1884) and master's degrees (1887).
[4] He served as an assistant to Bishop Nicholas Matz at the cathedral in Denver for a year and a half before returning to Chicago and resuming his duties at All Saints.
[3] After Reverend Thaddeus J. Butler was appointed Bishop of Concordia in 1897, McGavick succeeded him as pastor of St. John's Parish in the Near South Side of Chicago.
[4] He earned a respected reputation during his first year at St. John's after paying off the parish's debts, renovating the church building, and establishing a Sunday school for Italian children.
[4][10] That same year, in addition to his duties as an auxiliary bishop, he was appointed pastor of Holy Angels Parish in Chicago.
[11] One of his assistants at Holy Angels was Father William Richard Griffin, who would again serve with McGavick as auxiliary bishop of La Crosse (1935–1944).
In 1915, Archbishop George Mundelein appointed McGavick to be spiritual director of the Holy Name Society in the archdiocese.
[12][13] Pope Pius XI appointed McGavick to succeed the late James Schwebach as the fourth Bishop of La Crosse, Wisconsin, on November 21, 1921.