Penn, the younger brother of current UFC welterweight contender BJ Penn, won his professional mixed martial arts debut, defeating Paul Gardiner via rear naked choke in just 70 seconds at a ProElite show in Honolulu, Hawaii.
Gardiner came out strong, surprising Penn with a takedown. Penn looked for a guillotine, then quickly scrambled to take Gardiner's back, where he choked him out without even fully sinking his hooks in.
Gardiner had been 1-0 in his pro career, winning his April debut fight via first-round TKO.
"I did what I wanted to do," said a smiling Penn, who may have gotten the biggest ovation of the night from the crowd in his home state. Prior to the event, the 30-year-old Penn said he would take his career on a fight-by-fight basis, but the welterweight gave no indication afterward if he planned to compete again.
Andrei Arlovski also emerged victorious on the card, winning for the first time since October 2008 with a third-round TKO over Ray Lopez. Arlovski (16-9) controlled the fight for much of the duration but had trouble finishing the durable Lopez.
Finally, midway through the third, he rocked Lopez with strikes from the top, and continued the hail of punches until the ref pulled him off. Arlovski had lost four straight prior to that.
Despite the fact that the event was called ProElite: Arlvoski vs. Lopez, the show finished with Kendall Grove vs. Joe Riggs in the main event slot, and Grove needed less than one minute to defeat Riggs, forcing him to tap to a standing guillotine choke.
Grove moved to 13-9 with one no decision.
In the other main card fights, Mark Ellis defeated Jake Heun via second-round rear naked choke, Drew McFedries uses strikes to force a second-round TKO over Garret Olson, and promising female star Sara McMann stayed unbeaten, moving to 4-0 with a third-round TKO over Raquel Pa'aluhi.