The 32-year-old actress posted the new photo with Affleck on Instagram while celebrating his birthday Sunday.
The picture shows de Armas and Affleck smiling for the camera as de Armas snaps the selfie. De Armas captioned the post with a heart emoji.
De Armas and Affleck were spotted on a motorcycle ride Saturday in Pacific Palisades, Calif. People said de Armas had Wyld Garage Co. custom build the motorcycle for Affleck's birthday.
De Armas and Affleck were seen riding together while wearing matching helmets.
"Ana surprised Ben with a new motorcycle with his and her helmets for his birthday. He loved it," a source told Entertainment Tonight. "They're both incredibly happy together, and going strong. Ben is in a great place."
Affleck and de Armas were first linked in March after meeting on the set of the upcoming film Deep Water. The couple went Instagram official in April while celebrating de Armas' birthday.
In May, Affleck and de Armas were featured in Residente's "Antes Que El Mundo Se Acabe" music video. The couple were shown kissing while on their trip to the desert for de Armas' birthday.
Affleck was previously married to Jennifer Garner and has three children, Violet, 14, Seraphina, 11, and Samuel, 8, with the actress. He told ABC News in February that he was open to a "meaningful" relationship.
Affleck most recently starred in The Way Back, released in March. De Armas is known for the film Knives Out and will appear in the new James Bond movie, No Time to Die.