And yet here he is, now 47 years old and retired from boxing, sitting on some heavy bags next to a cage not so unlike the one he saw for the first time, along with the American public, in November of 1993.
"I remember my manager told me, 'Man this thing ain't going anywhere. It's too far out there.' That's how it seemed at the time, but now look at it," he says and gestures at the expansive gym around him. "Who knew, right?"
Not Jimmerson. Not back then. He was a former Golden Gloves champion riding a 15-fight win streak. He'd had nearly 30 fights as a pro, and his career seemed like it was finally on the verge of taking off. Fighting a bunch of karate teachers and toughmen in front of a couple thousand people in Denver sounded like a relatively easy night of work.
"I thought it was a joke at first," he says. "They said I had to go in there with no gloves and fight some guy named Royce Gracie. I was like, I'm going to kill this man. I never heard of no Royce Gracie."
These days you can tell just from his face that Jimmerson has lived the life of a fighter. His friendly eyes sit surrounded by mounds of scar tissue and his nose is stamped into his face like a weathered monument to his battles in the ring.
He had his first pro boxing match at the El Cortez Hotel in San Diego in 1985. His last was at the Community Market in Danville, Va. in 2002. Somewhere in the middle came the two minutes of his life that MMA fans know him for.
"There was a [video] game called Street Fighter back in the day," Jimmerson says. "It was real popular, and it was the same kind of thing, matching up all these different fighters from all over the world. And the boxer, he was a bad guy. I thought it'd be like that."
It wasn't – not even close – but it's not the actual fight that people remember so much as Jimmerson's chosen attire.
He showed up in the Octagon that night wearing boxing trunks and one boxing glove on his left hand. His right – his power hand – was bare. It had the effect of making him look like a boxer who had been in the middle of getting ready for a fight when someone pulled the fire alarm in the locker room.
But appearances be damned, this was strategy, Jimmerson says now.
"The one glove, that was kind of a trick. I knew I was knocking cats out with fifteen-ounce gloves, so what am I going to do to someone with my bare hand? They had no idea who I was, so I wanted to wear the one glove so he'd think I wanted to hit him with that hand, but then I'd suck him in and hit him with the other, right? I told them I wanted to wear one glove and they were like, 'Fine, wear one glove.'"
The problem was that Jimmerson didn't know who Gracie was either, so he had no idea that he was about to get a lesson in submission grappling. He got his first clue that he might be in over his head during the introductions.
"When they said my name, two people clapped, and they were my cornermen," Jimmerson recalls. "Then there was this big roar for [Gracie], like the ground was shaking. That's the first time where I was like, who is this guy?"
Jimmerson never got the chance to suck Gracie in. Instead he was quickly put on his back by a takedown and then mounted by the jiu-jitsu black belt. Once there, Jimmerson admits, he was lost.
"I'm used to fighting one set of rules my whole life. I was down and I was waiting for the ref to break us up. Then he starts headbutting me and I'm like, man, he's cheating! But it was legal."
That's when Jimmerson realized he was in trouble. Instead of fighting some strip mall expert doing kung fu katas in the middle of the cage, he was fighting a trained professional who knew these rules and these kinds of fights much better than he did.
Rather than wait to find out just how gruesome this no-holds-barred fight could get, Jimmerson tapped out at 2:11 of round one, and without ever being subjected to a submission attempt or even any notable striking. It was Gracie's first fight in the UFC. It would be Jimmerson's last.
"I sometimes wish that I had known what I know now about it back when I first got into it," he says. "I just had no idea what to expect."
Being remembered more for what he wore on one night than for a lifetime spent in boxing is strange, he admits, but that's how it is even with meager levels of fame. The early submission though, that has earned him some scorn from MMA fans on the internet. They see the fight on YouTube and, without knowing anything else about him, label him a coward.
That part, says Jimmerson, is still a little tough to deal with.
"They say all this stuff to me, like I'm a punk, I was scared, this and that. But those people, they don't understand why I tapped out. It wasn't because I was afraid; it was because I didn't know where I was at. I didn't know what was going to happen, and I had a boxing career to think about."
It's been almost exactly eight years since the last time he stepped in the ring as a professional boxer. Since then he's filled his time training others, as well as working for Pepsi-Cola in St. Louis, which he left to move out to southern California when he heard the UFC was opening a gym here.
"I heard about it and I thought immediately, it's like peanut butter and jelly, you know what I'm saying? I was the first guy that fought Royce Gracie, first boxer to do the UFC. It makes sense."
Coaching is what he's most passionate about these days, he says. Whether he's teaching people the sweet science or demonstrating punching fundamentals for aspiring MMA fighters, he's happy.
"When I can see that I'm showing somebody something and they're getting it, they're picking it up, man, there's nothing better in the world to me. That's like food to me. It's nourishing to me to see that. That's why I love to teach."
It still amazes him that MMA and the UFC have grown like they have, but he says he's also very grateful for it. There's the job, for one thing, and occasionally some MMA fans will recognize the name, even if they don't know the face.
People can remember him for the one glove if they want, he says. That's fine. At least he was one of the men willing to give it a shot back when few other boxers would. No one can say he wasn't right there at the start of it all, wearing his one glove, figuring it out on the fly just like everybody else.