Logan Paul defended his WWE United States Championship at WrestleMania 40 on Sunday ... surviving an intense Triple Threat Match against Kevin Owens and Randy Orton!!

The Maverick made his presence known in Philly from the very beginning ... entering on a Prime Hydration truck and firing from a Prime bottle cannon before hopping in the squared-circle.

It was yet another impressive outing from Paul ... who showed serious athleticism throughout the lengthy match with his high-flying moves and other stunts.

Just like at WrestleMania 39, he once again had a Prime bottle mascot in his corner ... but it wasn't KSI behind the outfit this time around -- it was popular streamer IShowSpeed, who very well might have saved Paul from being eliminated from the match when he pulled him away from Orton's reach.

Orton got his revenge on Speed -- RKO'ing the internet personality on the broadcast booth -- and the dude appeared to be out cold.

Paul also had a bit of help from a pair of brass knuckles ... but it was a short-lived effort, as Orton ripped them away and handed them to the referee.

The fans let Paul hear it ... booing him and even chanting "Gatorade" during the event.

Paul secured the victory with a wild frog splash on Owens ... which was good enough to finish him off with a three count.