The couple welcomed a daughter - Della Rose Joel - who weighed 7 lbs 6.5 oz according to PEOPLE.
Although this is Roderick's first child, Joel, already has one daughter Alex Ray Joel, 29, with former wife Christie Brinkley.
The 66-year-old singer, most known for his song "Piano Man" married his fourth wife, Alexis Roderick, 29, on 4 July 2015.
The couple announced back in April 2015 that they were expecting their first child together.
In June, when asked how he felt about becoming a dad for the second time, Joel told UPI: "[It's] Pretty wild, huh? I've still got the mojo. I'm excited!
"I'm gonna spend a lot of time with this kid. I'm probably going to be able to spend more time with this kid than most people are able to spend with their children, because I don't have a regular job.
"I could be a stay-at-home dad for as long as I can stay alive."