Rousey made her mixed martial arts debut as an amateur on August 6, 2010. She defeated Hayden Munoz by submission due to an armbar in 23 seconds.
She entered the quarterfinals of the Tuff-N-Uff 145 lbs women’s tournament on November 12, 2010 and submitted promotional veteran Autumn Richardson with an armbar in 57 seconds.
Rousey faced Taylor Stratford in the Tuff-N-Uff tournament semi-finals on January 7, 2011 and won by technical submission due to an armbar in 24 seconds. She then announced plans to turn pro and was replaced in the tournament.
Rousey made her professional mixed martial arts debut on March 27, 2011 at King of the Cage: Turning Point. She submitted Ediane Gomes with an armbar in 25 seconds.
Rousey faced kickboxing champion Charmaine Tweet in an MMA bout at Hard Knocks Fighting Championship: School of Hard Knocks 12 on June 17, 2011 in Calgary, Canada. She submitted Tweet with an armbar in 49 seconds. Rousey has a 3-0 amatuer winning record in amatuer MMA competition, all fights combined were under 2 minutes.