Walt Disney, Viacom and CBS are among the 278 companies and firms that joined an amici curiae brief asking the Supreme Court to overturn the federal Defense of Marriage Act (DOMA).
The entertainment companies were joined by more than a dozen prominent tech firms, including Apple, Facebook, Google and Amazon.
Other Hollywood companies joining the brief include the Jim Henson Company and the Wasserman Media Group.
Amicus curiae (plural amici curiae) or "friend-of-the-court" briefs are filed by interested parties in cases in which they are not direct participants.
The companies' brief argues that DOMA "impairs employer/employee relationships" by forcing companies to treat employees differently from one another and adds undue compliance burdens on corporations.
On Wednesday, the Obama administration filed a separate brief also asking the Supreme Court to overturn the law.
The key issue in the case of United States v. Windsor hinges on the constitutionality of section 3 of DOMA, which bans federal marriage benefits to same-sex couples legally married under state law. The Supreme Court will hear oral arguments on the case on March 27.
Oral arguments in a separate case dealing with the constitutionality of California's Prop. 8 initiative banning same-sex marriage in the state will be heard on March 26. An amici curiae brief filed in that case includes Apple, Facebook, Cablevision and the Jim Henson Co. The brief argues that state bans on same-sex marriage violate the Constitution's due-process and equal-protection provisions.