The website claims the occasion was documented by a photographer and Kristen wept as they got hitched.
Kristen and Dax went to the office simply to obtain their marriage licence, an eyewitness shared.
However they decided to go the whole way when a court employee offered to marry them then and there.
The nuptials purportedly took place in a nearby courtroom which is what Kristen previously mentioned she wanted.
The pair began dating in 2007 and announced their engagement in 2010, however they stated they wouldn't wed until same-sex marriage was legalised in California.
Following the Supreme Court's ruling on the Defense of Marriage Act in June, Kristen tweeted Dax a second proposal.
"Now we're just waiting on our own laziness," Kristen admitted to E! Online earlier this month.
"I have to unfortunately report that we just haven't gotten it together on a Saturday to get to the court house,” she admitted. “But we have every intention to. We have every intention to. We wanna sign those papers. And I think we just found out that you can do it online now. What if we got married online? Print it out: ‘You guys, married! Married, everybody!' It's just out of laziness that we haven't actually done it yet."
In March this year, Dax and Kristen welcomed their daughter Lincoln.
None of them have mentioned the good news online so far, however Dax shared that he would be brushing up on fatherhood skills that night.
“It's Thursday, means there are parenting lessons on at 10pm. NBC,” he posted on Twitter.