Trinity Church is a parish church of the Church of Norway in Arendal Municipality in Agder county, Norway. It is located in the central part of the town of Arendal. It is the church for the Trefoldighet parish. It is also the seat of the Arendal prosti (deanery) in the Diocese of Agder og Telemark. The red, brick, neo-Gothic church was built in a cruciform basilica design in 1888 using plans drawn up by the architect Christian Fürst. The church seats about 850 people.

Arendal is a municipality in Agder county in southeastern Norway. Arendal belongs to the region of Sørlandet. The administrative centre of the municipality is the city of Arendal. Some of the notable villages in Arendal include Rykene, Eydehavn, Færvik, Strengereid, Kongshavn, Kilsund, Brattekleiv, Torsbudalen, Longum, Saltrød, Staubø, Vrengen, and Kolbjørnsvik. The offices of UNEP/GRID-Arendal are also located in the city of Arendal.