Donald Trump Jr. and his wife Vanessa Haydon Trump have welcomed their fourth child.

On Sunday, Oct. 21, the "Celebrity Apprentice" judge made the announcement on Twitter, adding that his wife and child are doing well.

"It's a BOY!!! @MrsVanessaTrump and baby are doing great," Donald Jr., 34, tweeted. He has yet to disclose further details about the baby's weight and name. 

The couple's new bundle of joy is the latest addition to their first three children: Tristan Milos, 1, Donnie John III, 3, and Kai Madison, 5. They announced Vanessa's pregnancy last May and asked their Twitter followers if they thought she was having a boy or girl. They also asked suggestions for baby names.

Donald Jr. is a real estate developer and currently oversees Trump International Hotel and Tower SoHo in New York City along with his sister Ivanka. The Trump Soho Hotel is also overseen by "Apprentice" season five winner Sean Yazbeck. 

Donald Jr. was a guest judge for several episodes of season five before sitting in for the entire season six. 

Donald Jr. married Vanessa in 2005. His mother, Ivana, is Donald Trump Sr.'s first wife. Ivanka, also helped judge "Apprentice. Donald Jr. also has a brother named Eric and two half-siblings from his father's second ex-wife, Marla Maples, and current wife Melania Knauss-Trump. 

NBC recently unveiled the cast of "The Celebrity Apprentice" 2013. It will be the first-ever all-star edition of the hit show. "All-Star Celebrity Apprentice" brings back 14 celebrity contestants from previous seasons to compete in business-driven tasks around New York City. 

"This season is going to be fantastic! We will have the first ever 'All-Star Celebrity Apprentice' with 14 of the best contestants from previous seasons. It's going to be another amazing season!" Donald Sr., who is also the show's executive producer and host, said.

"All-Star Celebrity Apprentice"  is set to premiere in March 2013.