First Unitarian Church in Budapest, Protestant church building in District V, Budapest, Hungary.

The First Unitarian Church in Budapest stands at Nagy Ignác utca 2–4 in District V, built into the closed street front rather than freestanding. Samu Petz designed the neo-Gothic complex, completed in 1890, with a pointed portal under a balcony and a copper-clad octagonal ridge turret. The single-nave church occupies the second floor, reached by stairs on both sides, and is 8 metres wide and 26 metres long, oriented east–west with a five-sided west end.

The first Unitarian congregation in Budapest held its first service in 1869, led by Ferencz József, and became an independent mother congregation in 1881 under pastor Derzsi Károly. The city donated a 600-square-fathom plot, and architect Samu Pecz designed the three-storey complex in 1885. The Vienna firm Holtzspach-Majorossy built it for 325,000 forints without the congregation's financial contribution, retaining profit rights for 50 years. The church was consecrated on 26 October 1890.

The congregation began with Ferencz József's first Unitarian service in Budapest in 1869, and the first entry in its church register that year was the baptism of Áron Buzogány's son Gyula. The building also houses the bishop's office of the Hungarian Unitarian Church since 1970. A memorial plaque to pastor Miklós Józan, the church district's first dean, was unveiled at the Alkotmány utca entrance on 7 November 2020.

The church sits on the second floor of the Nagy Ignác utca 2–4 building, reached by the neo-Gothic staircase on either side; the street entrance is on the Alkotmány utca side. The ground floor and upper floors hold offices, apartments and the bishop's office, so visitors should head for the stairs rather than the shopfronts. The building is integrated into the closed street front, not free-standing.

A memorial plaque to Miklós Józan, Budapest pastor, first dean and later bishop of the Unitarian Church, was unveiled on 7 November 2020 at the Constitution Street entrance of the Nagy Ignác Street building. The church declared 2020 a Józan memorial year. In the courtyard stands a statue of writer Géza Páskándi, unveiled on 25 May 2023 for his 90th birthday.