This is the American ballerina's first child with the 73-year-old Rolling Stones frontman, while Jagger is already a father to seven other children -- daughters Karis, Georgia May, Jude and Elizabeth, and sons James, Lucas and Gabriel, all from prior relationships.
The couple's newest family member was born Dec. 8 in New York and is named Deveraux Octavian Basil Jagger. Octavian means "born eighth" in Latin.
"I'm so [in] love with my baby Deveraux Jagger. Thak you @lizzyjagger for the sweet introduction," the new mama wrote.
ET confirmed Hamrick’s pregnancy in July. Jagger, who was first linked to the dancer in June 2014, was previously married to Bianca Jagger from 1971-1978 and has also dated Jerry Hall and the late L'Wren Scott.