Joe Rogan is riding hard for Justin Baldoni ... tearing into Blake Lively and Ryan Reynolds for lawyering up against him.

It all went down on "The Joe Rogan Experience" over the weekend, where Joe called out Blake and Ryan for screwing up big time -- his guest, Brendan Schaub, agreed, saying the backlash they’re getting is well-earned for trying to weaponize the #MeToo movement against Baldoni.

Joe slammed Blake and Ryan for trying to hijack "It Ends with Us" -- the movie where all this drama started -- saying plain and simple, it’s Baldoni’s film ... and his production company, Wayfarer Studios, owns the rights to the film and its sequel.

Rogan said Baldoni had a solid case against Blake and Ryan -- while Schaub took it up a notch, comparing it to Johnny Depp’s legal war against Amber Heard, and praising Baldoni for "doing it for the boys."

Joe acknowledged Blake’s claim that Baldoni entered her room while she was breastfeeding -- but pointed out Baldoni had receipts, showing she had literally asked him via text to come in.

Rogan wrapped it up by torching Blake and Ryan for rolling in with their lawsuit, thinking their Hollywood clout would keep them untouchable.

As you know … Baldoni’s dropped some heavyweight lawsuits -- including a $400 million case against Blake, Ryan Reynolds, and Leslie Sloane ... accusing them of launching a full-on smear campaign to wrestle control of "It Ends with Us" out of his hands.