TIME made the list to honor young digital moguls, health pioneers and teachers from around the globe, along with athletes who are making a difference in the world.
Rousey, 26, is the first-ever woman to sign with the Ultimate Fighting Championships (UFC), a mixed martial arts company that previously had no interest in holding female fights.
In Feb. of 2013, Rousey beat bantamweight contender Liz Carmouche in the first WMMA fight in UFC history.
"Rousey is updating the face of female athletics through her tough skills and commercial successes," Time wrote in their report.
Rousey is slated to fight fellow bantamweight Miesha "Cupcake" Tate on Dec. 28 in Las Vegas, Nev, in a UFC title fight.
Rousey vs Tate will serve as the co-main of the historic UFC 168 card headlined by a middleweight title fight between Anderson Silva and Chris Weidman.
Besides fighting, Rousey has been making quite a name for herself as an actress.
Rousey will appear in "Fast & Furious 7" and "The Expendables 3" next year, and she's expected to have many more acting gigs come her way in the months ahead.
The star judoka was also on ESPN The Magazine's 15th anniversary issue earlier this year, and she has appeared on many late night talk shows.
Rousey was on "Jimmy Kimmel Live" this past week, and she made an appearance on "Conan" just a few months back.