He's gonna like this one, Jim!!!

Tony Romo transitioned back into athlete mode Thursday ... sinking a 30-foot chip-in for an eagle at a pro tournament -- and the shot was EPIC!!

The ex-Dallas Cowboys QB (and Jim Nantz' NFL game broadcasting partner) hit the links as a sponsor exemption at the Korn Ferry Tour's Veritex Bank Championship in Arlington, Texas ... and it didn't take long for him to shine.

On his first hole of the day -- the Par 5 10th at Texas Rangers Golf Club -- Romo knocked his second shot just short of the green, and was looking to chip it close with his 3rd shot to set himself up for a birdie look.

The thing is ... Romo hit the chip shot so well -- IT ACTUALLY WENT IN!!!

Side angle footage showed just how difficult of a chip it really was ... Romo had to navigate a big hill in order to bury the ball in the cup.

Of course, Tony's a hell of a golfer and this isn't anything too new for the 41-year-old -- so his celebration was muted, with nothing more than a small fist pump and a wave.

Romo -- who's played a handful of times at pro events before -- is currently doing well at the event ... he's even on his scorecard through five holes so far.