He was the spiritual protector and chaplain general of the Orléans obedience of the Military and Hospitaller Order of Saint Lazarus of Jerusalem from 2012 to 2021.

His father was an army officer who fought for the allied forces in World War II, based at RAF Cosford, who was later imprisoned in Czechoslovakia in the 1950s.

[3] Duka graduated from Tyl Grammar School in Hradec Králové in 1960 and worked in a factory and as an apprentice locksmith before entering military service from 1962 to 1964.

[3] On 6 January 1969 he made his temporary profession as a member of the Dominicans and on 22 June 1970 he was ordained a priest by Cardinal Štěpán Trochta, Bishop of Litoměřice.

[3] From 1990 to 1998, he was a lecturer in the Faculty of Theology at Palacký University in Olomouc, teaching Introduction to Sacred Scripture and biblical anthropology.

In August 2015, Duka banned a conference by Jeannine Gramick, an American nun specialising in pastoral care for LGBT people, as well as the screening of a Polish film about a homosexual priest.

Since I do not think people with this sexual orientation are discriminated against in our country, it is not right for us to advocate things which are in direct conflict with the Catholic Church’s teachings.

"[13] In 2016, Halík criticized Duka for allegedly dissociating himself from the pope and for being too close to the Czech president Miloš Zeman.

[15] Halík also criticized Duka in October 2016, for accepting the highest state award from President Miloš Zeman,[16] telling Právo: "On the 28 October national holiday, when Miloš Zeman was bestowing a medal on Dominik Duka for his support for Miloš Zeman, I remembered the words a former Pope, who commented on the death of Cardinal Richelieu — He said if God exists, the cardinal will probably have a lot to explain to him; if God does not exist, the cardinal did his job perfectly.

"[17] In February 2018, a group of Czech Catholic laymen wrote a letter to Pope Francis, expressing concern about Duka's closeness to Czech politicians including Václav Klaus, Miloš Zeman and Tomio Okamura, and urging him not to extend Duka's term as archbishop when he submitted his resignation as required upon turning 75 in April 2018.