The decision follows consultation with the Justice Department and the Supreme Court's ruling in June on the constitutionality of the Defense of Marriage Act.
"It is now the department's policy to treat all married military personnel equally," Defense Secretary Chuck Hagel said in memo Wednesday to senior Pentagon officials.
The Defense of Marriage Act prohibited the federal government from recognizing any marriage other than that between a man and a woman. In late June, the Supreme Court cleared the way for legally married gay couples to be recognized under federal law.
The Associated Press reported last week that Hagel was considering the new benefits proposal.
The benefits will be made available to same-sex spouses as long as the service member provides a valid marriage certificate. But earlier plans to provide benefits to unmarried gay partners have been dropped, officials said Wednesday.
Military personnel in a same-sex relationship who are stationed in a state that does not permit same-sex marriage will be allowed to take leave for travel to a jurisdiction where they can marry legally.
"This will provide accelerated access to the full range of benefits offered to married military couples throughout the department, and help level the playing field between opposite-sex and same-sex couples seeking to be married," said Navy Lt. Cmdr. Nate Christensen, a Pentagon spokesman.
Defense officials estimate there are 18,000 same-sex couples in the active-duty military, National Guard and Reserves and among military retirees. It's unclear how many of those are married.
A Pentagon ban on gays serving openly in the military was dropped in September 2011.
Copyright 2013 The Associated Press.