Reedus shares a 19-year-old son Mingus with his ex Helena Christensen and referenced them both, as well as Diane and the family's new addition, in the caption.
Kruger, 42, and Reedus, 49, started dating in 2017, after Kruger ended her decade-long relatonship with Joshua Jackson.
Ahead of Thanksgiving, Kruger shared a message with her fans, thanking Reedus for a life-changing year.
“Favorite time of the year ♥️ Happy Thanksgiving everyone ♥️ I have A LOT to be thankful for this year and I count my lucky stars to have met you @bigbaldhead and for sharing life’s many blessings with you,” she said at the time.
Earlier this month, Kruger said that being a mum makes her feel like a "superhero."
"She's very little, but I'm tired," the actress shared with Extra. "I feel like a superhero right now."
Now we just need confirmation of the little one's name.