Moceanu was born on September 30, 1981 in Hollywood, California to parents Dimitru and Camelia. She has one sister, Christina. Moceanu's parents, who had both been gymnasts in their native Romania, had early aspirations for her gymnastics career: while she was still a toddler, they tested her strength by allowing her to hang from a clothesline.

Moceanu began gymnastics classes in Illinois at the age of 3 1/2 and later trained at LaFleur's club in Florida. In 1991, at the age of 10, she moved to Houston, Texas, where she became one of the last gymnasts to be trained by the legendary Romanian coaches Marta and Béla Károlyi. She began competing internationally at a young age, earning her first U.S. National Team berth in 1992. At the age of 10 1/2, in the spring of 1992, she earned five medals--gold in the team event, uneven bars, vault and floor exercise; silver in the all-around--at that year's Junior Pan Am Games.

Under Károlyi's tutelage Moceanu became the U.S. Junior National Champion in 1994. In 1995 she repeated her success as a senior, becoming the youngest gymnast ever to win the U.S. Championships. She was also the youngest member of the American team at the 1995 World Championships in Sabae, Japan. Moceanu did not disappoint, earning the highest American placement in the all-around competition and becoming the only American gymnast to win an individual medal, a silver on the balance beam.

Moceanu's national and international successes, combined with her plucky, bubbly attitude, earned her attention and a wide fan base both in and out of the gymnastics community. In the months leading up to the Atlanta Olympics, she was one of the most recognizable faces of USA Gymnastics, eclipsing more decorated teammates such as Shannon Miller and Dominique Dawes. Before the Olympics, Moceanu was featured in Vanity Fair and wrote an autobiography, Dominique Moceanu: An American Champion. The book was highly successful and ranked number seven on the New York Times' Best Sellers List.

Moceanu was expected by many to be a major medal threat at the 1996 Olympics. However, following the 1996 U.S. Nationals, where she placed third in the all-around, she was diagnosed with a stress fracture in her right tibia. Her injury forced her to sit out of the Olympic Trials, but she was petitioned onto the team on the strength of her Nationals scores.

At the Olympics, still struggling with her injury and sporting a heavily bandaged leg, Moceanu contributed heavily to the team gold medal, turning in such strong performances that she qualified for the event finals on balance beam and floor exercise. However, she faltered in the last rotation of team finals, falling on both of her vaults. She only advanced to the all-around finals as a replacement for injured teammate Kerri Strug. Small mistakes cost her a medal, but she still placed a respectable ninth. In the balance beam event final, Moceanu suffered a horrifying fall when she missed a foot on a layout and crashed into the balance beam on her head. She finished the exercise and went on to a strong performance in the floor finals later that day, finishing fourth and just missing a medal.

Post-Atlanta
Following the Atlanta Olympics, Moceanu participated in numerous events and professional gymnastics exhibitions, including a 100-city tour, before returning to competition. With the retirement of the Károlyis, she began training with other coaches at Moceanu Gymnastics, a gym constructed and run by her family.

Out of peak form, Moceanu placed ninth at the 1997 US Nationals. She participated in the 1997 World Artistic Gymnastics Championships in Lausanne, Switzerland, leading a new and mostly inexperienced US team. She was elected team captain, and qualified for the all-around final, but the competition was not a positive experience for her.

By 1998, however, Moceanu returned to top form. Under the tutelage of her new coach, Luminita Miscenco, she adjusted to a significant growth spurt and developed a clean, elegant style. She was selected for the American team at the 1998 Goodwill Games, where she became the first and only American to ever win the all-around title. In doing so, she defeated reigning World all-around champion Svetlana Khorkina, as well as the World silver and bronze medalists, Simona Amanar and Elena Produnova. Many consider this competition to be the highlight of Moceanu's career.

In late 1998, Moceanu was in the news for another reason--she left home and sued for legal emancipation from her parents in order to regain control of the money she'd earned as a gymnastics professional. In the resulting court case and television interviews, Moceanu stated that her father had squandered her sizable earnings and had an abusive, controlling nature. The court approved her petition for emancipation and control of her finances. However, Moceanu did eventually reconcile with both of her parents.

Training with Mary Lee Tracy at the Cincinnati Gymnastics Academy (CGA), Moceanu placed 8th at the 2000 U.S. Nationals. She qualified for the Olympic Trials, but was forced to withdraw with a knee injury.

2000-2007
In the fall of 2000, Moceanu participated in a post-Olympics national exhibition tour. She also participated in one of the post-Athens Olympics gymnastics tours in 2004, the "Rock N' Roll Gymnastics Championships".

After a five-year hiatus from elite gymnastics, Moceanu announced a return to competition in 2005. However, injury kept her from competing in the 2005 Nationals. She remained committed to her comeback efforts, training on floor and vault.

In the summer of 2006, Moceanu was invited to attend the USA Gymnastics national training camp. She also competed at the 2006 US Classic, where she performed decently on vault, successfully executing a full twisting Tsukahara vault. On floor she went out of bounds on her tucked full-in pass and fell on her double pike, posting one of the lowest FX scores of the meet.

In a decision that proved to be somewhat controversial, Moceanu was not able to qualify to the 2006 U.S. National Championships. Moceanu stated that she had been informed that she would advance to Nationals by attending the National Training Camp and competing at least two events at the Classic. Despite meeting these requirements, she was not able to qualify to Nationals based on her Classic performances. Moceanu appealed this decision with USA Gymnastics, but the ruling was not overturned.

Moceanu is currently a full-time business management student at John Carroll University in Cleveland, Ohio, and expects to graduate in the spring of 2009. She also coaches part-time at a gymnastics club in Cleveland and conducts clinics and private lessons around the country.

On November 4, 2006, Moceanu married long-time boyfriend and former Ohio State gymnast Dr. Michael Canales in Houston, Texas. At age 26, Moceanu gave birth to a daughter, Carmen Noel Canales. Carmen was born on Christmas Day, 2007, just after 3 p.m. at Cleveland's MacDonald Women's Hospital. The baby weighed 7 lbs., 7 oz. upon delivery and measured 18.5 inches.