Vincent Autin and Bruno Boileau will become the first same-sex couple to marry in France.
Autin is a 40-year-old gay rights activist who also works for the Montpellier tourist office, while Boileau, 30, is a civil servant.
The ceremony in Montpellier today will be joined by over 200 friends and family, as well as a government minister.
Autin and Boileau met via a website for fans of pop singer Christophe Willem, who came to fame through the La Nouvelle Star talent TV show.
The couple would reportedly like to adopt a child after marrying.
Gay marriage was signed into law by President François Hollande on May 18 after the French National Assembly approved the final draft of the legislation last month.
The issue divided France and caused people in their tens of thousands to take part in public protests. On Sunday, more than 150,000 people marched through Paris in protest against the new law.
France is the ninth country in Europe to legalise gay marriage, joining the Netherlands, Belgium, Spain, Portugal, Sweden, Norway, Denmark and Iceland.
Beyond Europe, gay marriage is legal in Canada, South Africa, Argentina, New Zealand and Uruguay.