Yes, you heard right ... Henry says he's the best ever.
The UFC's Flyweight champ (125 lbs.) came through the TMZ office days before his UFC 238 fight against Marlon Moraes -- where Cejudo's fighting for the Bantamweight title (135 lbs.) -- and entry into the exclusive champ-champ club.
For Cejudo ... it comes down to personal accomplishments -- and he believes there ain't a man or woman on Earth with a better resume.
"I feel like I'm the greatest combat athlete of all-time, and the credentials speak for itself," Henry tells us.
"Who's won Olympic gold medal? Who's won a flyweight title? Who's gonna fight for a second belt? Nobody. It's me."
FYI -- HC won a gold medal in freestyle wrestling at the 2008 Summer Olympics in Beijing.
It's not just a second belt he's after ... Henry also wants to be #1 on the UFC top pound-for-pound list -- where he's currently ranked 4th.
BTW, speaking of belts ... shout-out to Cejudo's coach, Eric Albarracin, for holding his ... thing's heavy.