He studied at the monastic school of Einsiedeln in Switzerland, where he took the Benedictine habit in 1854, made profession on 14 October 1855, and was raised to the priesthood on 11 September 1859. A year later he accompanied his confrère, Martin Marty, afterwards Bishop of St. Cloud, to the newly founded monastery of St. Meinrad in Indiana.
Having arrived there in September, 1860, he taught in the seminary and attended a few neighbouring missions. While stationed at Terre Haute, Indiana (1864), he organized the German Catholic Congregation of St. Benedict, for which he built a church in 1865. In 1869, when St. Meinrad was raised to an abbey and Father Marty became its first abbot, Father Fintan was appointed prior and master of novices.
While Abbot Marty worked among the Native Americans in Dakota (1876–80), Prior Fintan was administrator of the abbey, and, upon the resignation of the former, who had meanwhile been appointed Vicar Apostolic of Dakota, Fintan was elected Abbot of St. Meinrad on 3 February 1880, and received abbatial benediction from Silas Chatard, Bishiop of Vincennes, Indiana on 16 May 1880.
He enlarged the college, founded the Priory of Subiaco in Arkansas and the Priory of St. Joseph in Louisiana, and obtained from Rome the permission to erect the Helvetico-American Congregation of Benedictines, of which he became the first president. When St. Meinrad's Abbey was destroyed by fire on 2 September 1887, he rebuilt the monastery on an even greater scale, founded a commercial college at Jasper, Indiana, and assisted in the foundation of the Priory of St. Gall in North Dakota.
- This article incorporates text from a publication now in the public domain: Herbermann, Charles, ed. (1913). "Fintan Mundwiler". Catholic Encyclopedia. New York: Robert Appleton. The entry cites:
- Necrologies in Paradiesesfrüchte, III (St. Meinrad, Indiana, 1898), 65-8;
- St. John's University Record, IX (Collegeville, Minnesota, 1898), 31-2;
- Revue Bénédictine, XV (Maredsous, 1898), 188-90.