The crowd on hand apparently greeted Flair with his signature "Woo" catch phrase, and he happily acknowledged them with a wave.
Flair, 64, was often popular with the wrestling crowd even though he was a heel for most of his career.
His in-ring antics often included rule-breaking, strutting and shouting of his "Woo!" catch phrase, but the fans still cheered for him.
"I don't see him, but the 'Woooos!' from the crowd tell me Ric Flair is back in the building," Raimondi tweeted.
MMA Fighting reporter Ariel Helwani confirmed the report that Flair was in the house at UFC Fight Night 35.
“@MrBONE747: @arielhelwani Did Ric Flair just show up? All I hear is WOOOO and the are on the ground' I figured the same," Helwani tweeted.
Since Flair received so much positive feedback from his cameo at UFC Fight Night 35, it's clear there's a huge crossover fan base between pro wrestling and MMA.
At least one MMA journalist didn't seem too thrilled with Flair's cameo at the event, as SB Nation's Luke Thomas hinted that the wrestling great has seen better days.
"Ric Flair looks like he's been ridden hard and put away wet. What a disaster," Thomas tweeted.
Flair is semi-retired from pro wrestling, but he still makes appearances at events.
"The Nature Boy" has a career that spans over 40 years, including stints with the NWA, WWF and TNA.