Moraes was born on his relatives' farm in Quintana, São Paulo, Brazil, but grew up on the ranch his father managed in Cachoeira Paulista. He is of Portuguese descent on his father's side. He grew up wanting to follow in his father's footsteps, but started riding bulls when he was 15. At age 17, he rode in his first professional rodeo in Brazil, and placed second in his third rodeo, making nine times as much as he did riding a tractor on the ranch his father managed. Shortly after this, he quit school to ride bulls full-time.
Moraes began his career at small rodeos throughout Brazil, eventually becoming a regular winner on that circuit. After being encouraged by a former PRCA bull riding champion, Charles Sampson, he set a goal of riding full-time in the United States. After winning Brazilian national titles in 1992 and 1993, he moved to the United States in 1994, riding on both the Professional Rodeo Cowboys Association (PRCA) and PBR circuits.
He immediately emerged as a major star, winning the average at both the Calgary Stampede and the NFR, as well as winning the year's PBR title. Most notably, Moraes became only the third man in history to ride 10 out of 10 bulls at the NFR.
Moraes would again win the average at the NFR in 1996, and in 1997 was on track to win his second PBR world title until disaster struck in the form of a broken leg during that summer, forcing Adriano to sit out the rest of the year while Michael Gaffney overtook him for the world title. Moraes did become the first man to win a second PBR world title, which he won in 2001. His success on that circuit was instrumental in the expansion of the PBR tour to include events in Brazil. He went on to win a third PBR title in 2006, just narrowly beating out fellow Brazilian, Guilherme Marchi, despite suffering from severe back spasms during the PBR Finals. Adriano was the first bull rider in the PBR to win 3 World Champion Bull Rider titles. In that year, he won an all-time series record of $1.36 million—more than three times as much as any other rider. At the end of the 2006 season, his all-time earnings on the PBR circuit were $3.37 million, also a record. Moraes has been honored for his accomplishments with a life-size bronze statue of him on Little Yellow Jacket that stands at the entrance to the new PBR headquarters building in Pueblo, Colorado.
Moraes announced in January 2008 that the 2008 Built Ford Tough Series season would be his final season of bull riding. He qualified for his last PBR Finals in October/November 2008. His last ride saw him buck off of a bull named Grey Dog, as Adriano failed to qualify for the championship round. It was an emotional moment and, waving at the cheering crowd, he left the arena in tears, saddened that his career has come to an end.
Moraes' overall PBR career earnings at career's end total nearly $3.5 million. In 2011, he received the ultimate honor from the PBR Heroes and Legends Celebration: the Ring of Honor.
Moraes qualified for the PBR World Finals a total of 14 times (1994–98 and 2000–08, though he did not compete at the 1997 Finals due to his broken leg).
Moraes and his wife Flávia, married since 1989, have four children (Victor, Jeremias, Antonio, Pedro) and currently have homes in Tyler, Texas and Cachoeira Paulista. A devout Catholic who lists his favorite book as the Bible and the late Pope John Paul II as a personal idol, he is also a member of the Cancão Nova missionary community in Brazil. He and his wife opened a Canção Nova mission in Texas. Underscoring his religious devotion and athletic competitiveness, he chose to ride only half of the 1998 PBR season in order to participate in a religious mission in Brazil, but nonetheless finished fourteenth in that year's PBR standings, despite suffering another broken leg in the middle of the season.