Arnold Schwarzenegger's Son Joseph Baena Ready to Flex in Bodybuilding Debut

Arnold Schwarzenegger’s spitting image is done training in the shadows ... Joseph Baena is ready to hit the stage for his first competition!

TMZ Sports is told the 28-year-old is set to make his bodybuilding debut this Saturday at the NPC Natural Colorado State competition … officially stepping into the world his dad once ruled -- racking up seven Mr. Olympia titles and becoming the most famous bodybuilder on the planet.

For years, the big question has been looming: would Joseph ever make the jump? Well, they're nearing the finish line -- and we have new video of them preparing last week.

With his uncanny resemblance to Arnold, fans have been calling for it forever … and Baena’s been teasing the idea along the way, building a massive following in the fitness world while showing off a physique that looks straight out of “The Austrian Oak’s” playbook.

But now it’s real -- and way more serious than a few Instagram flexes.

Joseph’s already shown flashes of what’s coming -- he landed the cover of “Men’s Health” back in March 2022 -- and his social media has detailed his preparation through his diet, training, and posing.

Baena had said he didn’t want to live in Arnold’s shadow, even keeping his mom Mildred's last name. But inspired by his father’s legacy -- and after years of putting in work -- he’s embracing the bodybuilding lane.

The ex-Governator has been hands-on throughout the process, offering Joseph training tips and guidance as his look-alike son prepares for his first time under the bright lights.

Not a bad coach to have!