Gyöngyi Szalay started her successful fencing career with Tapolcai Bauxitbányász in 1978, competing at the international level beginning in 1989. She participated at two Olympics (1996, 2000), with her best result a bronze medal in individual épée in Atlanta. She won a bronze medal in the individual at the 1991 European Championship, a silver medal at the 1995 World Championship, adding in individual World bronzes both in 1997 and 1998. In the team event, between 1989 and 1999, she was a seven-time World Champion, twice a silver medalist, and the 1991 European champion.
After her sports career, Szalay-Horváth was active in the politics of her home town, Tapolca, as a Deputy Mayor (2002-06), a member of the Veszprém County Assembly, and a sport manager of the local government. She also worked as a fencing trainer in her hometown, and taught physical education in a local high school. She was the founder of the Balaton Fencing Club in Tapolca.