The actor shared a photo of him meeting his newborn grandson on Tuesday.
“First time I saw my month-old grandson, Ryder!” he wrote next to the photo on Instagram.
He is the second son of his son Cameron Douglas and his partner Viviane Thibes, who posted about the birth last month on social media, “Touching the planet Earth. Welcome my son … Ryder T. Douglas.”
Cameron also has a 3 year old daughter, Lua.
Douglas’ wife, Catherine Zeta Jones, also shared in her Instagram story her excitement for a new grandson: “And a new Douglas is born !!!! Welcome to the Ryder T Douglas world.”
Cameron is the son of Douglas from his marriage to Diandra Luker; they divorced in 1995. Douglas also has two children with Zeta.