On Aug. 19, the model shared the news on Instagram while posting a slideshow of different looks from her closet. The final image, snapped in her full-length mirror, showed her in a form-fitting white midi dress cradling a baby bump.
"Taaa daahhh !! #round2," she captioned the post, while also adding three baby emojis.
After the announcement many of Rosie's model pals commented with congratulatory messages.
Jason, who isn't nearly as active on social media as Rosie, has yet to comment, but they've both publicly stated that they'd like more children.
The "Hobbs & Shaw" star, 54, and the model, 34, began dating in 2010 and got engaged six years later. In 2017, they welcomed a son, Jack.
Despite having one child and now another on the way, the couple doesn't seem to be in any rush to exchange vows.
"We're looking forward to that time. It's also not a huge priority for us; we're so happy. I think it will be fun to do it when the baby's grown up a bit and he can be involved in the wedding," she told ET in 2018. "We've been so focused on our work for so long and Jack came along. We definitely talk about it, we're looking forward to that time. It's also not a huge priority for us, we're so happy."