The actress turned 32 on Thursday and recently celebrated with her beau in the great outdoors.
De Armas shared a handful of photos from her special day on Instagram, which featured several snapshots of her with Affleck, 47, making her relationship with the actor social media official.
She shared nine photos, including two of herself and Affleck holding onto each other.
Another picture featured an elaborately decorated cake, complete with candles in the shape of the number 32.
"Thank you all so much for the birthday wishes and love," the "Knives Out" star wrote in the caption, which she also repeated in Spanish. "Cheers to another great year."
Reports of their romance swirled in March when the two were spotted smooching at the airport.
“They are definitely dating,” a source told People magazine at the time.