Legislative changes allowing homosexuals to register same-sex civil partnerships came into force in Latvia on Monday after the relevant amendments were passed in November last year.
The first same-sex couple tied the knot shortly after midnight, Latvian radio reported.
"The introduction of the civil partnership is an important signal that all families in Latvia will be protected, valued and recognized," Kaspars Zālītis of the Dzīvesbiedri (Life Partner) movement said.
"This long-awaited moment will change the lives of many people for the better," he added.
Latvian President Edgars Rinkēvičs, who came out as gay in 2014, and Prime Minister Evika Siliņa praised the change on X.
The legislative change, which remains controversial in Latvia, does not make civil partnerships equivalent to marriage, as was made clear in law when the amendment was passed.
The Latvian constitution still defines marriage as a union between a man and a woman.