Robert Kraft's son had to personally vouch for him!!!!

It all went down on the Mercedes-Benz Stadium turf after New England beat the Rams ... when the comedy icon was held up on his way to the confetti party.

The video is great ... Hart thinks security is just jokin' around not letting him through the gates -- when he suddenly realizes they ain't!!!

Kevin tries to crack a couple jokes to get through ... but still no dice!!!

Enter Patriots president Jonathan Kraft ... who rolls up to security to save the day -- telling everyone, "He's good! He's good! And, his wife!"

If this all feels familiar ... it's 'cause it is -- remember last year Hart was denied the chance to head up to the stage to celebrate the Eagles' Super Bowl championship???

For his part ... Kevin was able to joke about the whole thing afterward -- penning a social media post with a bunch of laughing emojis.