Orthodox Church may refer to:
- Eastern Orthodox Church, the second-largest Christian church in the world
- Oriental Orthodox Churches, a branch of Eastern Christianity
- True Orthodox church, a movement within Eastern Orthodox Christianity
- Orthodox Presbyterian Church, a confessional Presbyterian denomination located primarily in the United States
- Orthodox Presbyterian Church of New Zealand, a denomination formed in the 1960s led by George Mackenzie
- State church of the Roman Empire, Roman Empire's state religion after AD 380