The New England Patriots did it big for Mike Vrabel's birthday ... surprising the coach with one of the team's biggest superfans -- Bon Jovi!!

The Super Bowl champ turned the big 5-1 on Friday ... and while he had a loud 2026 with all things Dianna Russini, the vibes were much better with a celebration at training camp.

Pats owner Robert Kraft led the charge ... enlisting the rookie class to serenade Vrabel with a rendition of "Happy Birthday," with the team mascot, Pat Patriot, standing nearby.

After the song, Pat took off his head ... and it turns out the rocker was dressed up as the beloved character!!

The reveal put a big smile on Vrabel's face ... and he explained how JBJ has always been a big Pats fan -- even back when he was playing for the team.

Bon Jovi also addressed the roster ... saying he'll be rooting for them this upcoming season, as always.

Vrabel's been all over the headlines in recent months after pictures of him cozying up with the NFL insider were published by Page Six ... leading Russini to resign from her position with The Athletic, and the coach to seek counseling with his wife.

So when he's blowing out the candles on his birthday cake on Friday, we assume he'll be wishing for a drama-free 51st year.