St. John's Court House, Courthouse and national historic site in St. John's, Canada.

St. John's Court House stands at the corner of Water Street and Duckworth Street, built in 1901–04 in Romanesque Revival style. The hillside site makes it read as six storeys from Water Street and three from Duckworth Street. Sources differ on the architect: William Tuff Whiteway or William H. Greene. It houses the Supreme Court of Newfoundland and Labrador.

The first courthouse and jail on this site opened in September 1730. A larger building from 1831 burned in the 1840s, and its 1847 successor was destroyed by the Great Fire of 1892. The present building was constructed in 1901–04; its cornerstone was laid on October 24, 1901, by the Duke of York, later King George V.

Before the Confederation Building opened in 1960, the courthouse also housed the provincial premier, the Colonial Secretary and Cabinet, so law and government shared the same rooms. The Registry of Deeds, Companies and Securities and the St. John's Department of Public Works were later moved out to the Confederation Building.

The building stands at the corner of Water Street and Duckworth Street, so the two entrances sit at different levels of the hillside. It still serves as the seat of the Supreme Court of Newfoundland and Labrador, so courtrooms and offices are in active use; visitors should check access before entering.

Before the Confederation Building opened in 1960, the courthouse also housed the offices of the premier, the colonial secretary and the cabinet, along with the Registry of Deeds, Companies and Securities. The building was designated a National Historic Site on January 15, 1981.