Billy Joel and his new wife Alexis have welcomed a new baby girl, Della Rose Joel.

The excited news was first reported on the singer's official website. Della Rose was born at 7 lbs., 6.5 oz.

Joel also has a 29-year-old daughter, Alexa Ray Joel, with ex-wife Christie Brinkley.

"Celebrating the arrival of my precious little sister this week //," Alexa posted to her Instagram this week.

"With Pop and his Darling's happiness at their peak // As long as you are growing in love and loyalty // You're cultivating a life worth more than royalty.

#Shamelessly Sentimental #SappyBigSis #MySiblingsAreTheGemsOfMyLife."

Alexis Joel Is the fourth wife of Billy.

The couple was married in a surprise ceremony in July.

They tied the knot during their annual Fourth of July party at Joel's Long Island estate.