The 5th US Circuit Court of Appeals in New Orleans found Texas can require clinics to meet the same surgical standards as hospitals.
This may require all but seven of the state's abortion clinics to close.
In August, a lower court ruled such a requirement was unconstitutional, placing an undue burden on women seeking the medical procedure.
Republicans and other conservatives in Texas say the law will protect women's health.
But critics argue the law is a backdoor way to outlaw abortions, which have been a constitutional right in the United States since a landmark Supreme Court ruling in 1973
"This is a devastating day for Texas women," Jennifer Dalven, an attorney for the American Civil Liberties Union, told US media following the ruling on Thursday.
"The court's decision ignores the medical experts, who have recognised that these laws hurt women, not help them."
The appeals court ruled Texas could enforce restrictions on abortion clinics while the constitutionality of the state law - signed by Republican Governor Rick Perry in 2013 - is weighed.
Many of the state's abortion clinics have already closed in the wake of the law, which requires doctors performing abortions to have hospital admitting privileges.
If the law stands up to further appeals, clinics would be forced to make expensive upgrades to meet new legal standards.
In August, US District Judge Lee Yeakel ruled the law was less about public safety and instead about limiting access to abortion services.
Republican Attorney General Greg Abbott - tipped to win the Texas governorship in November - has championed the controversial law in court.
"This decision is a vindication of the careful deliberation by the Texas legislature to craft a law to protect the health and safety of Texas women," Lauren Bean, a spokesman for Mr Abbott, said following the ruling.
A US appeals court has ruled Texas can enforce restrictions on abortion clinics under a contested state law.