Soares was born to a middle-class family in Bandra, Maharashtra. Her family never had any relation with the modelling world. After having schooling at Bombay, she pursued her education from St. Xaviers. Madhu Sapre was the former Indian model who inspired Soares in modelling. Diandra was in a relationship with Gautam Gulati during her stay inside the Bigg Boss house. In 2016, Diandra made a web series called 'Do It Like Diandra'.
Soares has been active in the field of modelling since the age of 16. Her first assignment was for Tips and Toes and her first show was for McDowell's. In 1995, she was crowned as Miss Bombay, and that helped her to get contracts from various leading brands like Dinesh Suitings, VIP Lingeries, Tillsbury whiskey. She has walked for many international fashion shows in her career which were conducted by Gucci, Leonard Paris, Emanuel Ungaro, Sonia Rykiel, and Miami Fashion Show.
Soares is noted for her bald looks on the ramp. Designers opened and closed the shows with Soares in the Lakme Fashion Week. In September 2013, she shaved her head again. Soares commented that it was done for religious reasons and by going bald she felt spiritually empowered. She also added that her bald head might prevent her entry to many fashion weeks. She once again shaved her head during her session in Big Boss 8.
Soares was a contestant in the popular celebrity stunt show Fear Factor: Khatron Ke Khiladi in its 4th season in 2011. She became one of the popular contestants and survived to the end and became the first runner up. Diandra was then a contestant in the popular dance reality show Dance Ki Takkar in 2013. She got eliminated in the 9th week along with Priya Jhangiani.
Soares became a contestant on the Indian TV reality show Bigg Boss in its eighth season which started airing in September 2014 on Colors. She was evicted after 12 weeks on 14 December 2014 (Day 84).