A Klay Thompson impersonator has been BANNED for life from Warriors home games ... after he allegedly fooled arena personnel into believing he was the Golden State star, allowing him access to not just the building, but also the basketball court.

"Banned bc I walked past 5 layers of security guards (who willingly let me through security without asking for ID) & shot around on the court for 10 minutes," Dawson Gurley announced on social media.

And, Daws isn't kidding about the ban ... he posted a photo of a letter from a Warriors executive laying out his punishment.

"You deliberately deceived Chase Center building personnel by impersonating a GSW employee," the letter read, in part.

The disciplinary letter goes on to say Daws -- who isn't denying the allegation -- can't ever come back. They also threatened him with a trespassing charge.

For his part, Daws thinks the suspension is BS! He says he actually had a ticket for the game ... saying it isn't his fault security didn't stop him.

"I also spent 10K on tickets which they are not refunding. Why should I be banned because their security is incompetent?" Dawson asked his followers.

10 bands is obviously a lot of money to waste. But, the Klay impersonator says he doesn't have any regrets.

"Was it worth it to lose 10K on tickets and be banned for life? Absolutely. I was an NBA player for 10 minutes bro."

During those 10 minutes, Daws even had time to take a photo.

It's not the first time Gurley's received attention for impersonating the All-Star. He pranked fans during the 2018 NBA Finals, sitting courtside, dressed as Klay. That video has millions of views.

Side note: the real Klay Thompson had 21 points in Monday's game 5 win. The Warriors are one game away from winning an NBA title.