Arona was most recently reported to have signed with the UFC and planned on debuting with the promotion later in 2010. He never did and in the summer of 2011, Arona announced his retirement.
In early 2012, Arona reportedly came out of retirement. He was rumored to face Dream veteran Satoshi Ishii in Brazil.
- Ricardo Arona vs. Andrei Kopylov - The fight was the MMA debut of Ricardo Arona.
- Ricardo Arona vs. Fedor Emelianenko - The fight was in the first round of the Rings King of Kings 2000 tournament. Both fighters came in undefeated and it was Arona's first loss.
- Ricardo Arona vs. Hiromitsu Kanehara - The fight was for Rings.
- Jeremy Horn vs. Ricardo Arona 2 - The fight was for Rings.
- Ricardo Arona vs. Dan Henderson
- Ricardo Arona vs. Murilo Rua - The fight was a large grudge match.
- Quinton Jackson vs. Ricardo Arona - The fight was to decide who would face Pride middleweight champion Wanderlei Silva. The fight featured one of the most brutal slams in MMA history, delivered by Jackson and knocking out Arona.
- Ricardo Arona vs. Dean Lister - The fight was in the opening round of the Pride 2005 middleweight grand prix.
- Ricardo Arona vs. Wanderlei Silva 1 - The fight was in the semifinals of the Pride 2005 middleweight grand prix.
- Mauricio Rua vs. Ricardo Arona - The fight was the finals for the Pride 2005 Middleweight grand prix. Arona had defeated Wanderlei Silva in the pair's first fight earlier in the night and Mauricio Rua had defeated Alistair Overeem in THAT pair's first fight.