Oana Mihaela Ban was born on January 11, 1986 in Cluj-Napoca, Romania.
Ban first rose to prominence as one of Romania's top junior world-class gymnasts. She competed in her first Romanian national championships in 1998, winning the floor exercise event in the junior division. The following year, she was invited to join the Romanian national team, and began working with coaches Octavian Belu and Mariana Bitang at the elite training facility in Deva. Success in major international junior meets soon followed, including a first-place finish at the Top Gym tournament in Belgium and a bronze medal at the 2001 European Youth Olympic Days.
With her early January birthdate, Ban missed the eligibility cutoff for the 2001 World Championships by a mere eleven days. She was forced to wait until 2002 to make her international senior debut. At the 2002 World Artistic Gymnastics Championships in Debrecen, Ban won a silver medal on the balance beam, one of Romania's only victories of the competition. In 2003, Ban had a similarly strong showing, contributing to the Romanian team's silver medal at the 2003 World Artistic Gymnastics Championships and placing fifth in the all-around final.
Oana's career highlight came at the 2004 Summer Olympics in Athens, where she, along with teammates Monica Rosu, Alexandra Eremia, Catalina Ponor, Daniela Sofronie and Silvia Stroescu, won the gold medal in the team competition. Ban contributed heavily to the Romanian victory, competing on three events in the team finals. Individually, she qualified for both the all-around and the floor exercise final. However, an injury sustained on her last event in the team competition forced her to sit out both competitions and essentially ended her Olympic experience. For Ban, the situation was unfortunate: she had qualified to the all-around in an impressive third place; her qualifying floor score would have been good enough for a silver medal.
Ban retired from gymnastics after the Olympics; she is currently pursuing her education.