Mucklow added a sweet caption about her new family: "Welcome To The World Our Beautiful Baby Boy @andytcarroll You Are My Rock. Love My Boys More Than Anything. Best Feeling In The World! #BabyCarroll #LittleAC."
The couple have not yet revealed the name of their newborn, but have used the hashtag #LittleAC for the time being.
Although #LittleAC is the reality star's first child, he is Carroll's third, who already has a daughter, Emilie, five, and a son, Lucas, three, from a previous relationship.
The dad-of-three expressed his joy on his own Twitter account, joking about the "nine months of cooking" their newborn has had.
Welcome To The World Little AC!! 9 Months Of Cooking And What A Wonderful Job You Have Done… https://t.co/nDe04QSbGl— Andy Carroll (@AndyTCarroll) June 15, 2015
The couple have been dating for nearly two years and got engaged in November 2014 when Carroll whisked Mucklow away for a weekend in Rome.
Mucklow has documented her pregnancy on social media.
She shared some touching photos displaying her bump, alongside Carroll, as well as an extravagant baby shower and gender reveal.
Oh, and of course some West Ham accessories for their son who no doubt will be wearing them straight away...
Congrats to the couple!