BEYONCÉ gave birth to baby BLUE IVY CARTER Saturday night in New York’s Lenox Hill hospital.

Beyoncé and Jay-Z welcomed the baby girl in a private wing of the hospital.

Music kingpin Russell Simmons  confirmed the arrival of the baby superstar joy, Tweeting “congrats to my good friends Beyoncé and Jay-Z.”

A very pregnant Beyoncé had checked into the hospital Friday night under the alias “Ingrid Jackson” a hospital staffer told the NY Daily News.

Beyoncé and her hubby, (real name Shawn Carter), rented out the hospital’s entire fourth floor for $1.3 million.

After 11 p.m. Saturday night, even doctors and nurses were barred from entering the fourth floor.

Hospital workers even placed tape over security cameras and had forced employees to turn in cell phones in an effort to keep security tight, a source said.