The transportation secretary, who had previously spoken about his desire to become a father, said he was "overjoyed" by the news.
The couple shared sweet photos of the newborn on social media.
The singer and partner Alev Aydin shared their baby's unique name and some tender snapshots on Instagram.
Husband Alec Baldwin told one doubter to "mind your own business" after the arrival of baby Lucia.
“The love i feel for this tiny human is beyond my understanding," Malik wrote in an Instagram post announcing his daughter's birth.
The "Total Bellas" stars, who gave birth one day apart, named their sons Matteo Artemovich Chigvintsev and Buddy Dessert.
The "Bridesmaids" star had hinted at motherhood on "Saturday Night Live."
The couple had kept quiet about their growing family amid reports that they welcomed a third child.
"Our hearts are full, our eyes are tired," the country singer wrote on social media.
Bundle of joy Banks Violet Bair is the "Lizzie McGuire" star's second child.