The former Gossip Girl star wowed in a satin floral patterned frock and yellow heels while in Los Angeles on Monday, 13 April.
Blake is back to work after giving birth to daughter James in December, her first child with actor husband Ryan Reynolds.
She's starring in new movie The Age of Adaline, about a young woman who becomes ageless after an accident.But her immortality comes into question when she meets a man…
Blake - who played Serena in Gossip Girl - recently spoke to Extra about embracing her character and the style of that time period, saying: "This movie wasn't about this woman always looking her very best, you look at the time period that Adaline came of age, in the 1950s there was no such thing as putting on sweatpants and Uggs and going to the grocery store.
"You put on your gloves, your pillbox hat, matching cardigans -- women really presented themselves."