The "House of Cards" star showed off her engagement ring Friday night at fashion designer Diane von Furstenberg's "Journey of a Dress" party, E! News reported.
A source told E! that the couple got engaged at a party at the Chateau Marmont.
"They're both just really cool," the source said. "They were talking to people but weren't overdoing it with PDA. They would have their arms around each other and were so chill."
Wright, 47, and Foster, 33, began dating after co-starring in the 2011 crime drama "Rampart."
The upcoming marriage will be Wright's third -- she was married to Sean Penn for 13 years and Dane Witherspoon for 2 years -- and Foster's first.