Hayes broke the news this week in an entry on his Web site that began: "I very rarely make comments about my private life."
He then announced that he had married his boyfriend of two years, Richard Cullen, in a civil partnership ceremony in London on June 19.
The 34-year-old singer-songwriter said it was the most significant event of his life.
Hayes said he feels lucky to live in an era that recognizes gay marriage. "I'm proud of who I am, and after what felt like an eternity, I'm finally in a place where my heart is secure and content. And I can finally make sense of all of the searching."
He told fans not to expect updates because he still believes "that families and relationships are not commodities to be sold off for public consumption."
Hayes was briefly married in the late 1990s.
He is about to begin a six-month stint in a London studio to record his third solo album.
Hayes and Daniel Jones formed Savage Garden in 1994. The duo, known for their hits "I Want You" and "Truly, Madly, Deeply," disbanded in 2001.