In 1964, he finished all his studies in Rome and returned to Gniezno in Poland. He became chaplain of the Dominican and Franciscan Sisters and teacher of religion in the house for delinquent minors. He worked as Secretary of the Seminary of Gniezno and as notary for the Curia and the metropolitan tribunal and also as defender of the bond.
In December 1967, he worked in the Secretariat of the Primate, and for 15 years was one of Cardinal Stefan Wyszyński's close collaborators. As the personal chaplain of the Cardinal, he accompanied him on his journeys within Poland and to Rome. He exercised varied responsibilities in the Commissions of the Polish Episcopate and taught Canon Law at the Academy of the Catholic Theology in Warsaw. He participated in several congresses on this topic in Poland and abroad. In 1972 he was named chaplain to His Holiness, and in March 1976 be became Canon of the Metropolitan Chapter at Gniezno.
On 4 March 1979, John Paul II named him Bishop of Warmia, in the northeast part of Poland and was consecrated on the feast of S. Adalberto, on 21 April, in Gniezno.
After the death of Cardinal Wyszyński on 18 May 1981, he was named Archbishop of Gniezno on 7 July 1981, in union "pro illa vice, ad personam" with the Archdiocese of Warsaw. As Bishop of Gniezno he became also the Primate of Poland. [The title of Primate of Poland was conferred on the Archbishop of Gniezno by Pope Martin V in 1418 and confirmed by Leo X in 1515, every Primate of Poland to the time of his election, even if he is not a cardinal, has the right to wear the red "zucchetto" of a cardinal, a privilege already accorded in 1600 and confirmed by Benedict XIV in 1749.]
On 25 March 1992, with the restructuring of the Church dioceses in Poland, John Paul II dissolved the union "ad personam" of Gniezno-Warsaw, naming as Metropolitan Archbishop of Gniezno Bishop Henryk Muszyński. The Holy Father decided that the title of Primate of Poland should remain linked to the historical heritage of S. Adalberto in the Archdiocese of Gniezno and confirmed that Cardinal Józef Glemp, Archbishop of Warsaw, who had custody of the relics of S. Adalberto, which were venerated in the Cathedral of Gniezno, should continue to bear the title of Primate of Poland. On 1 November 2006, the Holy Father Benedict XVI confirmed the title of Primate until reaching 80 years old.
Cardinal Glemp acted as President of the Episcopal Conference of Poland for 23 years, from 1981 until March 2004.
President delegate to the 1st Special Assembly for Europe of the Synod of Bishops (1991).
Archbishop emeritus of Warsaw, 6 December 2006.