Al Horford Guarantees Return To Celtics, I Want Another Title!

It took Al Horford 17 years to win his first NBA title ... but he's hoping he can double his ring collection next season -- telling TMZ Sports he's 100% NOT retiring and is returning to the Boston Celtics.

We spoke with the longtime vet fresh off his team's championship win over the Dallas Mavericks in the Finals ... and while many might assume he'd consider ending his career on the highest of notes, the 38-year-old told us that's absolutely not the case.

"There's no question about it," Horford said while working a shift at Raising Cane's in Boston. "I don't know why those speculations were out there, that I was, like, retiring. But I'm still playing and I'm very excited for next season."

There's a good reason to be excited -- Horford knows what it's like to win back-to-back titles, as he did with the Florida Gators in college.

We asked him what he's gonna tell his teammates about the challenge of defending a title ... and Horford explained it's part soaking it all in, part getting right back to work.

As Horford enjoys being a champ once again, he decided to spend some of his day meeting with thousands of Cs fans while working a shift at Raising Cane's.

He worked the counter and kitchen ... but don't worry, he made time to enjoy some of those delicious tenders.