In terms of religious affiliation, ethnic Ukrainians are exclusively Christian, professing an ancient and traditional form of Christianity: - Eastern Greek (Byzantine) rite: Ukrainian Orthodox Church, and the Ukrainian Greek-Catholic church, primarily in western Ukraine. Ukrainians were baptised en masse c. 988 by the Grand Duke of Kyiv, Volodymyr, thereby adopting Greek-Christianity from Byzantium. The first metropolitans and bishops (seated in Kyiv and Halych) in Ukraine were Greeks, later natives. Prior to 1700, the Ukrainian Orthodox Church was subject to the Greek Patriarch in Constantinople (Byzantium-Istanbul). Three hundred years ago, it was sold to the Moscow patriarch. After independence in 1991, the Ukrainian Orthodox Church separated from Moscow Patriarch and Filaret (Denysenko, who had been metropolitan of Kyiv for 40 years) was elected the independent Ukrainian Patriarch.

The largest group of Ukrainians confess to belonging to the Ukrainian Orthodox Church headed by Patriarch Filaret (born Denysenko). The Ukrainian Greek-Catholic Church (numbering over 5 millions believers) was headed by Lyubomyr Huzar, until the election of Sviatoslav Shevchuk, and is subordinated to the Pope in the Vatican. Evangelical protestantism is booming in Ukraine - many Ukrainians recently became either Pentecostals or Baptists. Islam is foreign to Ukraine, some Muslims can be found among non-Ukrainian groups such as Crimean Tatars on the Crimean peninsula and Asian immigrants.