The baby girl arrived at 9:18am PT on Thursday morning (November 10th) weighing in at 7lb 5oz via caesarean section.
Rob was joined by his mother Kris Jenner and sister Khloe Kardashian for Dream's birth, and another of his siblings, Kourtney Kardashian, commented on the new arrival after seeing her brother's Instagram post.
Before giving birth, Chyna even posted a #mannequinchallenge video on her Instagram account and captioned it "Dream team".
So far, Blac's BFF Amber Rose has also taken to social media to publicly congratulate the pair.
Dream is Kardashian's first child.
News the couple had a daughter on the way was revealed on the September premiere of their new E! reality show. "Although Rob and Chyna have had turbulent times in their relationship, they face many important decisions head-on as the couple prepares for the birth of their baby".
She wrote: "Can't stop looking at her congrats @robkardashian @BLACCHYNA she's so beyond handsome, a dream". She looks exactly like him and Rob is thrilled.
The 61-year-old "momager" said recently: "I got to watch [the] delivery". It's truly a blessing.
"It was so handsome and I'm so excited and happy to have another grandchild!"
He wrote: "Today was fantastic I am so lucky!"
Chyna is also the mom of King Cairo, 4, with Tyga, so this will be her second child. It was so attractive and I'm so excited and happy to have another grandchild!