- The couple had not publicly confirmed they gave birth
- Neither of the babies were identified in the photos
The singer and the retired tennis star have been together since 2001 but are famously closed-mouthed about their relationship.
In December it was reported
that the pair had managed to keep a pregnancy under wraps and had welcomed twins Nicholas and Lucy in Miami, Florida.
Neither Iglesias nor Kournikova has ever publicly confirmed or commented on the births. But on Tuesday each posted photos with newborns on Instagram using the same caption: "My Sunshine."
Neither of the babies was identified by name.
Kournikova, 36, told Women's Health in 2011
that she was excited about becoming a mother someday.
"I absolutely want to have children, whether I have my own or adopt," she said. "I love taking care of people."
CNN has reached out to reps for the couple for comment.