The model, who is expecting her first child with boyfriend Zayn Malik, joined Jimmy Fallon via video chat on Thursday's Tonight Show, and officially confirmed that she is expecting.
"Thank you so much," Gigi said, after Fallon congratulated her on the big news. "Obviously, we wish we could have announced it on our own terms, but we're very excited and happy and grateful for everyone's well-wishes and support."
She also reflected on her recent 25th birthday, which she celebrated with only her closest family amid social distancing mandates, and explained how her wonderfully elaborate cake, which was designed to look like an everything bagel, related to her pregnancy news.
"My family brought out an everything bagel cake, which blew my mind because my craving has been everything bagels, and I eat an everything bagel every day," Hadid explained. "So I was already so excited that my birthday cake was an everything bagel. But then I found out that Buddy the Cake Boss made my cake!"
The celebratory confection, made by the famous Buddy Valastro, was "marble cake with chocolate chip buttercream inside," according to Hadid, who explained that the sweet treat actually got her super emotional.
"I don't know if it was my hormones right now or just quarantine emotionalness, but I cried about that every five minutes for, like, an hour, every time I thought about how Buddy made my cake," she said with a laugh. "I cried from happiness."
During her chat with Fallon, Hadid also dished on how she's been living in self-isolation during the coronavirus, and how that hasn't kept her from working and modeling. In fact, since the lockdowns began, Hadid has done two different Vogue shoots, which she's had to do with the help of her sister and her friend, who's living with them amid the quarantine.
"I did one for Italian Vogue where they sent a Chanel look, and I kind of made it a fun fantasy," Hadid said, referring to a snapshot of herself laying on a coach in her home and playing Mario Kart on her large TV while rocking the chic ensemble. "Obviously don't play Mario Kart while playing Chanel, but I made like a quarantine fantasy scene."
"American Vogue wanted to have clothes that were meaningful or told a story," she added, before explaining how both shoots were snapped by her friend, who is not a professional photographer but was down to help when she needed it.
"So she got a really easy fast route to photography stardom and now has two Vogue shoots under her belt," Hadid added with a laugh.
She's also gearing up for a tennis tournament for charity -- albeit a virtual tournament played with Mario Tennis, but she did get the best partner she could hope for: Serena Williams.
"She's such a great friend, and I'm her biggest fan, and we're gonna play doubles together!" Hadid exclaimed. "I've been practicing a lot, because if anyone is more competitive than me it's Serena and I cannot lose her friendship!"