"Mary and Heather have been in a committed relationship for many years, and we are delighted that they were able to take advantage of the opportunity to have that relationship recognized," the Cheney family said in a statement. "Mary and Heather and their children are very important and much loved members of our family and we wish them every happiness."
The couple, who live in Virginia with their two children, were married Friday in Washington, the Daily Caller reported.
Cheney said in 2004 he supported President George W. Bush's push for a constitutional ban on same-sex marriages, saying the question should be left to the states.
He reversed his position after leaving office, saying in 2009: "I think people ought to be free to enter into any kind of union they wish. Any kind of arrangement they wish. The question of whether or not there ought to be a federal statute to protect this, I don't support."