Showbiz
Rex Features
The child will be Costner's sixth and his second with Christine Baumgartner, joining 1-year-old Cayden in the family.
He also has three children - Anne, Lily and Joe - with Cindy Silva, and Liam with Bridget Rooney.
Costner's representative revealed that the star, who will release a country album with Modern West next month, is "ecstatic" at the news.
A source added that the pair are "so incredibly blessed right now as everything in their life is perfect".
More: Kevin Costner, Showbiz
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