The Supreme Court of Judicature Act (Ireland) 1877^[3] (40 & 41 Vict. c. 57) was an Act of the Parliament of the United Kingdom that brought about a major reorganisation of the superior courts in Ireland. It created a Supreme Court of Judicature, comprising the High Court of Justice in Ireland and the Court of Appeal in Ireland. It mirrored in Ireland the changes which the Supreme Court of Judicature Act 1873 had made in the courts of England and Wales.

The Act marked the fusion of the administration of common law and equity in Ireland, although not a merger of the jurisdictions themselves. Prior to the Act coming into force a litigant had to sue in equity in the Court of Chancery and at common law in the common law courts of the Common Pleas, the Exchequer, and the Queen's Bench. Mirroring earlier legislation applying to England and Wales, the Act merged these four courts to become a single High Court of Justice in Ireland; the old courts continued as divisions of the new court. Amending legislation later abolished all but the King's Bench Division and Chancery Division of the High Court.

The Act also created a new Court of Appeal in Ireland.

The "Supreme Court of Judicature in Ireland" that was created by the 1877 Act was abolished by the Government of Ireland Act 1920, s. 38;^[4] in its place were established a separate Supreme Court of Judicature for each of Northern Ireland and Southern Ireland, together with an overarching "High Court of Appeal for Ireland" with appellate jurisdiction for the whole of Ireland. The two new Supreme Courts of Judicature were constituted on a similar basis to the court they replaced, with both being made up of a High Court of Justice and a Court of Appeal (ss. 39, 40).