The 60-year-old actor confirmed on Tuesday's episode of The Talk that he quietly married Derek, 64, in 2020 after 20 years together.
Corbett shared the news with friend and The Talk co-host Jerry O'Connell.
"Jerry, I can't believe that I forgot to tell you that around Christmastime, we got married! Bo and I got married," Corbett said.
O'Connell said he noticed Corbett's wedding ring and congratulated the actor on his marriage.
"We're pretty private people. We didn't make an announcement. All of our friends and family knew," Corbett said.
"After 20 years, we decided to get married," he added. "We didn't want 2020 to be that thing that everybody looks back and hated. We thought, 'Well, let's get one nice thing out of it.'"
Corbett played Aidan Shaw on Sex and the City, which aired from 1998 to 2004 on HBO, and reprised the role in the 2010 film Sex and the City 2. It is unknown if Corbett will appear in the HBO Max sequel-reboot series And Just Like That...
"That's 20 years ago that we met," Corbett said. "We became fast buddies. We're super close. We like to go out."
Corbett most recently played Grady Bello on the ABC series Rebel and Dan Covey in the To All the Boys movies.