This will mark the first child for Burgess and the fifth for Green. The 48-year-old actor shares three sons -- Journey, 5, Bodhi, 7, and Noah, 9 -- with his ex-wife, Megan Fox. He is also dad to Kassius, 19, with Vanessa Marcil.
In one pic, Green happily smiles as he rests a hand on Burgess' growing belly. Meanwhile, the mom-to-be is glowing in a white bikini top as she soaks in the love.
Other photos show the couple walking on the beach and sharing a sweet kiss, while another standout shot features Burgess, 36, laughing as Green holds her.
Burgess also posed for a solo shot, giving fans a full look at her baby bump as she sports a white bikini.
When ET spoke with the couple last June, Burgess opened up about her hopes for motherhood.
"Kids have always been on the cards for me," she said. "One hundred percent, they've always been on the cards for me. So we'll see what the universe says will happen. We're just going to leave that open."
In the meantime, Burgess was thrilled to spend time with Green's children.
"I love spending time with the boys. I love having them in my life. They're amazing kids, so it's not a hard gig," she said. "... They're really cool little humans, and it's just [about] becoming good friends with them, learning what they like and playing with them and having a good time. They're really awesome."
The dancer praised Green as "an amazing dad," and the actor had some kind words for his girlfriend too.
"She's great with them, she really is. She's super fun. They love hanging out with her and doing things and she has a great connection with each one of them," he said. But she's also, she just instinctually sort of knows how to not be a stepparent in that way, but really just bond with them and love them. They feel really safe with her, and it's an amazing connection that they have."
"1 year ago yesterday my whole world changed. I just didn’t know it yet. You’re everything I’ve ever wanted in 1 person and the way you love me is something I couldn’t even have dreamed of," Burgess wrote on Instagram. "I never knew it existed until you. I love you baby, and I love doing life with you. 1 down, and all of them to go. :)."
Green and Burgess' happy news comes on the heels of Fox's engagement to Machine Gun Kelly. After Green's ex-wife made it official with her fiancé, a source told ET that the actor "couldn't care less" about Fox's engagement.
"He doesn't have any lingering romantic feelings for Megan or any anger. Brian is happy for her, but it really isn't affecting him one way or the other," the source said. "There's no bad blood or ill will between them at this point. He mainly feels indifferent towards [Fox's engagement] and is just glad they are co-parenting well together."