It's official: Duchess of Cambridge Kate Middleton and Prince William have welcomed a baby boy on Monday, July 22. "Her Royal Highness The Duchess of Cambridge was safely delivered of a son at 4:24 p.m. The baby weighs 8 lbs 6 oz," the Palace confirmed in a statement on Twitter. "The Duke of Cambridge was present for the birth. The Queen, The Duke of Edinburgh, The Prince of Wales, The Duchess of Cornwall, Prince Harry & families have been told and are delighted. Her Royal Highness and her child are both doing well and will remain in hospital overnight."

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Following the announcement, stars have taken to Twitter to congratulate the couple and welcome His Royal Highness. See what they're tweeting below:

PHOTOS: Royal family baby photos

Joan Rivers: "Congratulations to Kate & William on the birth of their baby boy! So relieved that his name won't include the words Ivy or Apple."

Melissa Gilbert: "Welcome royal baby boy!!!"

Louise Roe: "Congrats to William and Kate on the birth of their baby BOY! #RoyalBaby"

Ramona Singer: "A Prince! How exciting! #RoyalBaby #itsaboy"

Tiffany Thornton: "King is born! Loving this royal baby excitement. congrats to Will and Kate"

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Cheryl Cole: "Congratulations to William and Kate!! So happy they have a healthy baby and everyone is good. Can't wait to see him now #Royalbaby"

Jack Osbourne: "EPIC!!!! a new prince was born. its like real life Game of Thrones #royalbaby"

Josh Groban: "I know it's a boy, I'm watching it on the dang web cam. It's gurgling."

Chrissy Teigen: "BABY BOY good thing I didn't tweet my prediction of ginger girl."

Melissa Joan Hart: "Congratulations to the royal family on the new little Prince! Welcome to the world little man! #royalbaby" 

Lisa Rinna: "It's a BOY! #royalbaby I had a feeling it was a boy! Yay! Congrats Will and kate!"

This article originally appeared on Kate Middleton, Prince William Welcome Baby Boy: Stars React on Twitter