The 47-year-old British-Australian actress was accompanied by longtime partner Liev Schreiber, while Munn brought boyfriend Aaron Rodgers to the ceremony.
Watts wore an Armani Prive gown covered in purple and blue sequins and accessorized with a Bulgari necklace and clutch. Munn, meanwhile, chose a simple and sophisticated Stella McCartney dress in a bright orange hue.
Schreiber's film "Spotlight" was nominated for six Academy Awards and won Best Picture and Best Original Screenplay. He and Watts have been together since 2005 and share two sons, 8-year-old Sasha and 7-year-old Sammy.
"Out the door, just in time... On the arm of @lievschreiber my #winner here we go! Good luck #Spotlight #oscars," Watts wrote on Instagram prior to the ceremony.
Munn and Rodgers, a quarterback for the Green Bay Packers, started dating in 2014 and live together in Green Bay, Wisc., during the NFL season. The actress joked about her forthcoming role in "X-Men: Apocalypse" while speaking to E! News on the red carpet.
"I play a character who wields a sword," she said of Psylocke. "I became really proficient in swords. In my home in Green Bay, there's just a closet for swords. People are like, 'Will you not tell the kids this is here?' That's probably why I shouldn't be a parent any time soon."
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