The couple has been engaged since 2009 and have one daughter together, but they just got hitched on Thursday in a low-key ceremony at the Beverly Hills courthouse.
According to TMZ, the twosome originally headed to the clerk's office to get a marriage license but decided to tie the knot on the spot when an employee offered to wed them then and there.
The ceremony was conducted on site in a courtroom and Kristen reportedly shed tears of happiness during the wedding.
Kristen and Dax previously said they wouldn't get married until gay couples were able to wed, too.
"I don't feel appropriate taking advantage of a right that's denied to my [gay and lesbian] friends," Kristen said last August.
The Defense of Marriage Act was ruled unconstitutional in June, giving same-sex couples the right to have their marriages recognized by their individual states.
Congrats to the happy couple!