But the 10th U.S. Circuit Court of Appeals also left intact an existing temporary stay against a ruling requiring Utah to recognize the legitimacy of those marriages, giving the state time to seek a lengthier injunction from the U.S. Supreme Court.
Utah Attorney General Sean Reyes immediately vowed to do that in the next few days.
U.S. District Judge Robert Shelby in Salt Lake City ruled in December that a voter-passed law restricting marriage to heterosexual couples only was unconstitutional, clearing the way for same-sex couples in the socially conservative and heavily Mormon state to wed.
But the Supreme Court in Washington reinstated the gay marriage ban just 17 days later, issuing a stay of Shelby's ruling that halted further gay and lesbian nuptials until Utah's appeal of that decision had run its course.
Utah refused to confer legal recognition of gay and lesbian marriages performed in the interim, leaving those couples unable to proceed with adoptions, obtain spousal health insurance benefits or legally change their names.
Four newlywed same-sex couples then filed a separate lawsuit to get the state to recognize their marital status, winning a decision in May from another federal judge that their marriages were valid. But that judge also temporarily stayed his own ruling to let Utah petition for a lengthier injunction pending appeal.
The 10th Circuit on Friday denied that request for a permanent injunction.
Utah argued that legal recognition for newly married same-sex couples before the final outcome of the underlying legal battle over gay marriage would cause greater confusion.
Were the state to prevail, Utah officials said, gay and lesbian marriages performed last winter would be invalidated, stripping away the benefits conferred on them.
But the 10th Circuit said Utah failed to show irreparable harm would result from letting already married gay couples obtain spousal benefits.
The same three-judge panel in June upheld Shelby's decision. It marked the first time a federal appeals court had ruled on the merits of such a case since the Supreme Court decided a year ago that legally married same-sex couples nationwide were eligible for federal benefits.
Reyes said on Thursday he would appeal Shelby's ruling to the Supreme Court rather than seek reconsideration from the full 10th Circuit.
There are now 19 states, plus the District of Columbia, where same-sex marriage is legal. In another nine states, including Utah, federal judges have struck down bans on same-sex marriage but the rulings have been put on hold pending appeal.