Rousey fought Bethe Correia on August 1, 2015, in Brazil, at UFC 190, winning the bout by knockout 34 seconds into the first round. Rousey dedicated the match to "Rowdy" Roddy Piper, who died the day before, commenting that Piper was one of her inspirations and had endorsed her use of his nickname.
In her seventh title defense, Rousey faced Holly Holm in the main event at UFC 193 on November 15, 2015. Despite being a heavy betting favorite, Rousey was unable to get Holm to the ground and had no answer for Holm's superior striking. Early in the second round, Holm knocked Rousey out by a high kick, ending Rousey's three-year reign as champion. It was also her first loss. After the fight, Rousey and Holm were each awarded a Fight of the Night bonus of $50,000. She was also medically suspended by UFC on November 18, 2015. She was medically cleared on December 9, 2015.
At WrestleMania 31 in March 2015, the Four Horsewomen were seated in the front row. During an in-ring argument between The Rock and The Authority (Stephanie McMahon and Triple H), McMahon slapped the Rock and ordered him to leave "her ring". She taunted him, saying he would not hit a woman. He left, paused and walked over to Rousey to a loud ovation. He then helped her into the ring and said that she would be happy to hit McMahon for him. After a staredown, The Rock attacked Triple H. When he stumbled toward Rousey, she tossed him out of the ring. McMahon tried to slap her, was blocked and Rousey grabbed her arm, teasing an armbar, before throwing her out of the ring. Rousey and the Rock celebrated in the ring, while the Authority retreated with the implication of revenge. The segment was replayed and discussed throughout the next night's Raw with the commentators hyping a tweet Rousey made earlier that day, in which she implied a return to WWE with "We're just gettin' started...".
Rousey co-starred in The Expendables 3 (2014), marking her first role in a major motion picture. In 2015, she appeared in the film Furious 7, and played herself in the film Entourage.
In 2015, Rousey became the first woman featured on the cover of Australian Men's Fitness, appearing on their November edition.
In October 2015, Rousey became the first female athlete to guest host ESPN's SportsCenter.
In 2015, she raised money by auctioning signed T-shirts for the Black Jaguar-White Tiger Foundation, whose goal is to save big cats from circuses and zoos and provide them with the best lifestyle.
In April 2015, Rousey visited Yerevan, Armenia for the 100th anniversary of the Armenian Genocide. While in Yerevan, she visited the Tsitsernakaberd Armenian Genocide memorial.
Rousey once dated fellow UFC fighter Brendan Schaub. In August 2015, Rousey was rumored to be in a relationship with UFC fighter Travis Browne, who knocked out Schaub in a bout the previous year, after a picture of the two together appeared on Twitter and Browne's estranged wife Jenna Renee Webb accused the two of seeing one another. Browne was at the time still married and under investigation by the UFC after Webb publicly accused him of domestic violence in July 2015. Browne confirmed he and Rousey were together in October 2015. The next day, Rousey revealed that she was dating Browne. Rousey and Browne got engaged on April 20, 2017, in New Zealand and married on August 28, 2017 in Browne's home state of Hawaii.