The expectant mother shared a video of the cheeky announcement, which featured the couple's four other children – Carmen, 6, Rafael, 4, Leonardo, 3, and Romeo, 1 – on Instagram on Saturday.
In the adorable social media video clip, the miniature Baldwins head into a room where they each receive their own baby doll swaddled in a white blanket – only to unwrap the doll to reveal the sex of their new sibling.
"It’s a girl," Carmen exclaims after she unwraps her assigned doll and notices it's wearing pink.
"Our little reveal 💙💖. We are so excited!" Hilaria, 35, captioned her video.
The Oscar-nominated actor, 61, and the co-host of the “Mom Brain” podcast revealed last month that they were expecting a fifth child, sharing an ultrasound of their baby’s heartbeat with Hilaria’s followers.
"We have four kids. She wants to have another one. We’re having another one," he said. "We're gonna have a fifth baby."
However, when Nealon asked if Hilaria was pregnant, the “30 Rock” alum said: "No. No, no, no — not that I know of," he clarified.
In April, Hilaria revealed on social media that she had suffered a miscarriage.