Carolina Panthers Girl: I'LL NEVER SELL THIS FOOTBALL!!!

The adorable little girl who got a TD ball from Carolina Panthers RB Jonathan Stewart Sunday drove 100 miles with her family to attend the game ... and says she'll NEVER sell it, EVER!!

The lucky fan is 8-year-old Isabella -- who was at the game with her mom, dad and brother who are all Panthers super fans ... and usually sit in the nosebleed section when they attend games.

But Isabella's father, Kelly, tells TMZ Sports he splurged for the playoff game -- dropping more than $2,500 for the killer end zone seats because he felt something special was going to happen.

He was right.

Isabella became an instant Internet sensation due to her priceless reaction when Stewart singled her out and handed her the ball after scoring the 1st TD of the game.

"She let us all hold the ball, she was super excited!"

Kelly says he ordered a case for the ball the second he got home -- and it's currently on display in their living room.

"We're holding on to it forever," Kelly says ... "Never to be sold. We're too big of fans."