Baby on board.
"Getting so big so fast," he wrote, alongside a photo of himself with the infant strapped to his chest in a BABYBJÖRN Baby Carrier Mini. "Almost 2 months already."
Friends and fans quickly took to the post's comments section to gush over the sweet snap, including Brian's former Beverly Hills, 90210 co-star Lindsay Price who commented, "Your mini."
Brian, 49, and Sharna, 37—who went Instagram official with their romance in January 2021—welcomed baby Zane on June 28.
The couple's new addition is the first for Sharna and the fifth for Brian. The actor is also dad to kids Journey, 5, Bodhi, 8, and Noah, 9 (whose mom is his ex-wife Megan Fox) and 20-year-old Kassius (whose mom is Vanessa Marcil).
Shortly after Zane's arrival, Brian opened up to E! News about how he and Sharna ended up compromising on their baby's moniker.
"You know, naming boys is hard," he shared on July 1. "And finding a name that goes well with Green is really hard. So, I like the name Walker. Sharna liked the name Zane, and we kept going back and forth between the two as first names."
He continued, "I finally came to the conclusion one day of, 'You know what? This is Sharna's first child. I like Zane, it's an amazing name.' So I was like, let's do Zane Walker Green. And I think she appreciated it. And it's a really cool name."
As for what's next for Brian, the actor said is just looking forward to soaking up quality family time.
"I'm just spending as much time as possible with Zane, with the kids, and really just making it a family environment," he added. "What an amazing f--king year. What an amazing week."