The reality TV star and her fiance, Jionni LaValle, welcomed 6-pound-5-ounce Lorenzo Dominic LaValle into the world just before 3 a.m. at St. Barnabas Medical Center in Livingston, N.J., MTV said.
"The world just got another Guido!!!," a Polizzi rep told MTV. "Nicole, Jionni & Enzo are doing great!"
Later Sunday, Polizzi tweeted about how much she is already enjoying parenthood.
"Being a mom is an amazing feeling!!! I love my little man to death! Jionni is such a cute dad," she wrote. "I am SO IN LOVE with my son Lorenzo Dominic."
MTV congratulated Polizzi and her fiance and looked toward the newborn's possible appearance on "Jersey Shore."
"We couldn't be happier for Nicole and Jionni on the healthy delivery of their baby boy!," MTV said in a statement.
"We look forward to Lorenzo's first trip to the Jersey Shore and can't wait to see his first animal print onesie."
MTV has said it's bringing "Jersey Shore" back for a sixth season, with the 24-year-old Polizzi as part of the action, but the network has declined to offer specifics on how big a part she will play in the show, which is about hard-partying Italian-American friends.