​​​The majority of Romanians (86.5%) are affiliated with the Romanian Orthodox Church. Christianity reached Romania (or Dacia, as it was then known) under the Roman Empire as early as the 4th century AD. By the late 9th century, the Romanians had accepted a Slavonic liturgy, introduced by Bulgarian rule. Romania remained under the Patriarchate of Constantinople until the 19th century, and the church was only granted its own Patriarch in 1925.

The most significant minority religious groups are Catholics and Protestants, most of whom are part of the ethnic Hungarian population concentrated in Transylvania. Romania is home to small Jewish and Muslim communities, while the Romani people (around 3% of the population) blend Romanian Orthodoxy with their own spiritual traditions.