Before she began modeling, she worked for an event management company called Encore. She then worked as a public relations officer at BMG Crescendo, where she assisted in managing the careers of models Anaida and Mehnaz. On Anaida's recommendation she entered herself into the Miss India contest in 1997.
Diana Hayden won the Femina Miss India World crown in 1997, and then went on to win the Miss World crown in the same year. By doing so, she became the third Indian woman to win the Miss World pageant, after Reita Faria in 1966 and Aishwarya Rai in 1994.