That bout will mark the sixth fight for Penn in 18 months, a pace he hasn't approached since he was a 22-year-old UFC rookie and fought six times in 16 months from May 2001 to September 2002.
Yet despite his good health and the recent flurry of activity, Penn says he's not likely to fight much longer.
"I'm 31 right now. I want to fight a lot more until I'm 35 and then maybe call it quits," he said after overwhelming Hughes in just 21 seconds.
Whether Penn will one day change his mind and retire ahead of his projected date or fight well beyond it remains to be seen, but so does the rest of his future arc.
Penn said that for the first time in his career, he would let UFC president Dana White determine if he should fight as a lightweight or welterweight.
"Whatever Dana says, I'll go with that," he said, much to White's surprise.
Welterweight was the quick answer, judging from the UFC's immediate decision to pull Jake Ellenberger from a scheduled bout with Fitch in favor of Penn.
"I think he looks good at 170 and always has," Dana White said. "When he walked in that octagon, he had that crazy, talking-to-himself, swearing-to-himself hyped-up energy. He looked like he was ready to go, like the old BJ. He didn't look that way at 155."
It's a far cry from what could have transpired with a loss.
MMA Fighting asked White what he thought would have happened to Penn if Hughes had beaten him.
"I honestly think if BJ didn't win that fight, he would've retired," White said. "I think so. What do you do? You're BJ Penn, you just lost three in a row, two at 155, one at 170. I think he probably would've retired. I mean, I can't speak for BJ. Well, apparently now he says I can, but I don't know what he would've done. I think he probably would've retired. And it's the right thing to do. I hate to see these guys with legacies and guys that have been great to just keep hanging on too long."
Penn was only the second man to win titles in two UFC weight classes, capturing the welterweight title in the first fight of his trilogy with Hughes in January 2004 before taking the lightweight belt in January 2008 (Randy Couture was the first man to win titles in two divisions).
Approaching a full decade as a pro fighter, Penn realizes you're never the young man you see in the mirror who thinks he can fight forever. The end must come at some point, and as he nears his 32nd birthday (on Dec. 13), he is focused on staying as active as possible and proving that he can still win in two divisions.
"For years, people used to make such a big deal about jumping to different weights," he said. "Welterweights are a little slower and stronger. The lightweights aren't as strong and a little faster. So they both bring different challenges to the table. I dont know how I fit in with different ones. I feel I can do fine with both."