This article contains a timeline of significant events regarding same-sex marriage and legal recognition of same-sex couples worldwide. It begins with the history of same-sex unions during ancient times, which consisted of unions ranging from informal and temporary relationships to highly ritualized unions, and continues to modern-day state-recognized same-sex marriage. Events concerning same-sex marriages becoming legal in a country or in a country's state are listed in bold.

Summary of 21st century

The summary table below lists in chronological order the sovereign states (United Nations member states plus Taiwan) that have legalized same-sex marriage. As of June 2024, 38 states have legalized, although two of those have not yet come into effect. Dates are when marriages between same-sex couples began to be officially certified. When distinguished, the initial date is the date of legalization in the first subnational jurisdiction (state, province or constituent country), and the second is the completion date for all jurisdictions, not counting external territories (or in the case of the US, sovereign tribal nations). A dash indicates that same-sex marriage is not (yet) legal in all jurisdictions. This is the case for the Kingdom of the Netherlands, where the constituent country Sint Maarten has not yet legalized, and for the Realm of New Zealand, where the constituent countries of Niue and the Cook Islands have not legalized.

• State controls one or more territories where same-sex marriage is not performed or not recognized.

Ancient times

Various types of same-sex marriages have existed, ranging from informal, unsanctioned relationships to highly ritualized unions. Cicero mentions the marriage (using the Latin verb for "to marry", i.e. nubere) of the son of Curio the Elder, but he does it in a metaphorical form to criticize his enemy Antonius. Cicero states thus that the younger Curio was "united in a stable and permanent marriage" to Antonius. Martial also mentions a number of same-sex marriages, but always in derisory terms against people whom he wants to mock. At least two of the Roman Emperors were in same-sex unions; and in fact, thirteen out of the first fourteen Roman Emperors held to be bisexual or exclusively homosexual. The first Roman emperor to have married a man was Nero, who is reported to have married two other men on different occasions. First with one of his freedmen, Pythagoras, to whom Nero took the role of the bride, and later as a groom Nero married a young boy, who resembled one of his concubines, named Sporus. Adolescent emperor Elagabalus referred to his chariot driver, a blond slave from Caria named Hierocles, as his husband. He also married an athlete named Zoticus in a lavish public ceremony in Rome amidst the rejoicings of the citizens. In the Far East, same-sex marriage was recorded as normal and accepted by society in many of the native cultures of the Asia-Pacific region, such as Philippines. The Siwa Oasis in Egypt had a historical acceptance of male homosexuality and even rituals of same-sex marriage—traditions that Egyptian authorities have sought to repress, with increasing success, since the early 20th century. The German egyptologist George Steindorff explored the oasis in 1900 and reported that homosexual relations were common and often extended to a form of marriage.

Before 20th century

1900s

1901

1929

1960s

1963

1970s

1970

1971

1973

1974

1975

1979

1980s

1984

1985

1989

1990s

1993

1994

1995

1996

1997

1998

1999

2000s

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010s

2010

2011

2012

2013

2014

2015

2016

2017

2018

2019

2020s

2020

2021

2022

2023

2024