The Australian Capital Territory becomes the first Australian jurisdiction to legalize same-sex marriage with the Marriage Equality (Same Sex) Act 2013.

The Australian Capital Territory (ACT), known as the Federal Capital Territory until 1938, is an internal territory of Australia. Canberra, the capital city of Australia, is situated within the territory, and is the territory's primate city. It is located in southeastern Australian mainland as an enclave surrounded by the state of New South Wales (NSW). Exclaved from NSW after federation as the seat of government for the new nation, the territory hosts parliament house, High Court of Australia and the head offices of many Australian Government agencies.

Same-sex marriage, also known as gay marriage, is the marriage of two people of the same legal sex. As of 2025, marriage between same-sex couples is legally performed and recognized in 38 countries, with a total population of 1.5 billion people. The most recent jurisdiction to legalize same-sex marriage is Thailand.

The Marriage Equality Act 2013 was an act of parliament of the Australian Capital Territory Legislative Assembly that was intended to legalise same-sex marriage in the ACT. It was first presented to the ACT Legislative Assembly on 19 September 2013 by the ACT Attorney-General, Simon Corbell. The law intended to build on the existing recognition of same-sex unions in the Australian Capital Territory, which included recognition of de facto partners, civil partnerships and same-sex-only civil unions. The Act was passed in the Legislative Assembly on 22 October 2013. It came into operation on 7 November although wedding ceremonies under the provisions of the Act did not occur until 7 December 2013.

October 22 is the 295th day of the year in the Gregorian calendar; 70 days remain until the end of the year.