Rogan had already done some work for interviews for UFC but his appearance at the quickly put together UFC 37.5 event, which featured six fights - including a light heavyweight main event bout between Chuck Liddell and Vitor Belfort - was the first time we saw him on the commentary desk.
With a full head of hair and a voice that sounds a tad different to his tones these days, Rogan's first stint as a colour commentator was a huge moment.
He went back to hosting Fear Factor after this but returned at UFC 40 and has gone on to become one of the voices of combat sports - calling the biggest fights and moments and getting all the scoops in post-fight interviews.
He's 52 and bald these days but Rogan still makes fights feel special whenever he's cageside. Incredibly, his recent £82 million podcast deal with Spotify means he's in line to earn more than every UFC champion combined - excluding Conor McGregor of course.
The Joe Rogan podcast deal is worth $100 million. He's now richer then every UFC champion ever combined (excluding McGregor) pic.twitter.com/cUR4MSxA7Q- MMA Eejit :flag_ie: (@MMAEejit) May 19, 2020
We regularly see Rogan hop into the Octagon to get word from the fighters after they've finished slugging out but he was actually poised to fight in UFC himself back in the day.
Ridiculously, he almost fought Wesley Snipes in the UFC after the 'Blade' star was in trouble with the IRS and his agent approached the UFC about a one-off bout to put on a "crazy pay-per-view fight."
Snipes appeared set to face fellow actor Jean-Claude Van Damme, but Campbell McClaren, a UFC official at the time, wasn't keen on the 'JCVD' angle and had another name in the form of Rogan in mind.
"He's like 'nobody's gonna pay to see you and Jean-Claude Van Damme fight'", Rogan recalled on his podcast in 2016.
"You have to fight someone who was 'current.' So he said 'would you fight Joe Rogan? And he said 'Yup, let's do it.' So they came to me, and I went 'How much money?' And then they started talking, then I said 'OK, let's see what happens.'"
It never materialised in the end but Rogan, a brown belt in jiu-jitsu at the time, stated that he would have choked "the f**k out of" Snipes out.