He graduated from high school in Pécs in 1926. He entered the seminary in Jászó. He took his solemn vows on October 11, 1931. He was ordained a priest on November 30, 1931. He earned a degree in Hungarian and French from Pázmány Péter University and received his doctorate in the humanities in 1936; in 1941, he obtained a qualification as a private lecturer. In 1932, he was a scholarship student in Paris. He was a member of the Royal Historical Society in London (1956), the Institute of Language and Literature of the French Academy of Sciences (1962), the American Medieval Academy (1966), the Bavarian Academy of Sciences (1971), and the Hungarian Academy of Sciences (1983). He was a member of the International Commission for the History of Universities. His honors include: Palmes Académiques (1950), the Árpád Gold Medal (1962), Pro Ecclesia et Pontifice (1976), and the Middle Cross of the Order of Merit of the Republic of Hungary (1992). In 1982, he was granted the title of provost of St. Michael the Archangel on Margaret Island. Research into medieval literary history, cathedral and university education, and scholarly pilgrimage, combined with his enthusiastic and profound study of codicology and paleography, became an integral part of his daily life. Through a life of prayer that lay behind his work and diligence, he not only analyzed and systematized but also understood the thinking of the 12th–14th centuries, as well as the functioning and purpose of the Church’s institutions. As a true educator, he sought to pass on the values he had discovered in this way, the best example of which is the nearly two hundred publications in which he recorded his thoughts.

He left Hungary in 1947 and went to Toronto to join the Pontifical Institute of Medieval Studies, then moved to the United States a year later, where his name became associated with the Institute of Medieval Studies at the University of Notre Dame. He served as director of this Institute for twenty years. James L. John, a professor at Cornell University (Ithaca, N.Y.), stated that his work contributed significantly to the development of the humanities in the United States. His incredibly active work as a researcher and lecturer is well illustrated by the numerous invitations, honors, and memberships in professional societies that Gábriel Asztrik received both in the United States and in Europe. His most outstanding work is the cataloging and microfilming (approximately 17,000 reels) of the medieval manuscript collection at the Biblioteca Ambrosiana in Milan.

Professor Gábriel Asztrik, titular provost of the Saint Michael Provostry on Margaret Island, was one of the most renowned and well-known 20th-century members of the Premonstratensian Order, who, in faithful adherence to the order’s founder, St. Norbert of Xanten, faithfully passed on to his students the enduring values created through the Church’s work and his illuminating analyses of them. His unshakable faith served as an example to those around him and to all who came into contact with him, even if only for the briefest of conversations.

Breviárium-típusú kódexek. Bp., 1934. (Klny. Szt Norbert emlékkv.) - A római index és a fr. romantika. Uo., 1936. (fr-ul is) - Gosztonyi pp. és párizsi mestere. Uo., 1936. - M. diákélet a kk. Párizsban. Uo., 1938. - A kk. kéziratok kormeghatározása. Uo., 1938. - M. diákok és tanárok a kk. Párizsban. Uo., 1938. - A pozsonyi kódex eredeti kz-a. Uo., 1940. - A prem. kódexirod. Kassa, 1943. - Kk. kéziratok Mo-on. 1. Debrecen. Uo., 1943. - Mo-i Szt Margit. Uo., 1944. (ném-ül és fr-ul is) - Nürnberg Handschriften in Ungarn. Uo., 1944. (Ostmitteleuropäische Bibliothek 52.) - Les rapports dinastiques franco-hongrois in moyen-age. Uo., 1944. - A Notre Dame Egy. kiadványsorozatainak szerk-je: 1953: Texts and Studies in the History of Mediaeval Education. I-XIV; 1969: Publications in Mediaeval Studies. I-XXI. - 1949: az Analecta Praemonstratensia (Averbode, Belgium), 1970: a Mediaeval and Renaissance Studies (Western Case Egy., Cleveland, Ohio) szerk. biz. tagja. ezen kívül még több száz publikáció.