The 37-year-old model gave birth to a daughter called Esti on January 13, and Teigen has now taken to social media to share her happiness with her followers.
Alongside a family photo, Teigen – who also has Luna, six, and Miles, four, with John – wrote on Instagram: "She's here! Esti Maxine Stephens – the house is bustling and our family could not be happier. Daddy sheds nightly tears of joy seeing Luna and Miles so full of love, and I am learning you still need diapers with a C-section!? We are in bliss. Thank you for all the love and well wishes – we feel it all! X (sic)"
Teigen and Legend welcomed their newborn more than two years after she suffered a pregnancy loss with their son Jack.
In September, Legend admitted that the pain of losing his son will never "completely go away".
The award-winning musician explained that the heartbreak will stay with him for the rest of his life.
He said: "That pain is never going to completely go away. You're never exactly the same after you lose someone."
The pair have managed to cope with their heartbreak thanks to their other children.
The 44-year-old music star – who has been married to Teigen since 2013 – explained: "To have two little ones that we could dote on and nurture and enjoy ... They bring us so much joy.
"We just were able to hold each other through what was a very tough time."
Legend also revealed that he tempered his own excitement after Teigen announced her latest pregnancy.
The “Who Do We Think We Are” hitmaker said: "There's always this sense of cautious optimism because you know what it's like to lose one."