Simionescu triumphed in 1974 in the final of the jury women singles of the French Open against Sue Barker 6: 3 and 6: 3. During her professional career, she won a WTA individual title.
Between 1973 and 1979 she played for the Romanian Fed Cup team , for which she won 13 of their 20 games.
Simionescu had been in a relationship with Björn Borg since 1976 , whom she married on July 24, 1980 in Bucharest . The marriage was divorced again in 1984. She had another relationship with the racing driver Jean-Louis Schlesser , with whom she has a son.