Born in the southern Hungarian town of Kiskunhalas, she spent her youth as an athlete training for the heptathlon. Miklósa was Hungarian Junior Champion in the high jump. However, an accident forced her to switch career paths. Because of her good singing skills she chose to be a singer. At first, she sang at family gatherings, weddings, and formal celebrations. On one such occasion, a singing-master heard her and almost immediately began to teach the 16-year-old. Soon she went on to study music at the Franz Liszt Academy of Music in Szeged as well as in Milan and New York. She became a soloist at the Hungarian State Opera in 1990. Her signature role is the Queen of the Night from Mozart's The Magic Flute. She sang also at the Royal Opera House in London, at the Vienna State Opera, at the Metropolitan Opera in New York and many more famous opera houses. In 2004, she debuted at the Metropolitan Opera in her signature Queen of the Night role.