Supporters gathered in central Athens as the vote was announced.
Greece has legalised same-sex marriage - becoming the first Orthodox Christian country to do so.
The law passed by 176 to 76.
It also allows adoption, but doesn't cover gay men who want a biological child through a surrogate.
There was opposition to the bill from the Church - and some far-right parties.
Supporters gathered in central Athens as the vote was announced:

Daniel Kinahan Set To Apply For Bail
Former Swimming Coach George Gibney Jailed For Over 15 Years For Sexual Abuse Of Children
Robert Pether Returning To Ireland After Five-Year Iraqi Detention
Over 23,000 Teachers Beginning Industrial Action Today
New Funding Announced For Youth Services And Counselling In Kildare On World Mental Health Day
Jury In Triple Murder Trial Of Louth Family Sent Home
Appointment Cancellations Expected As Strikes To Take Place Next Week
Families Face Delays Arranging Funerals Amid Pressure On Post-Mortem Services