Dia Mirza was born on December 9, 1981, in Hyderabad, India. Her father, Frank Handrich, was a German graphics and industrial fair designer, architect, artist, and interior designer based in Munich. Her mother, Deepa, is a Bengali interior designer and landscaper who also volunteers to help alcoholics and drug addicts. After her parents divorced, her mother married Ahmed Mirza, a Muslim man from Hyderabad, and Dia adopted her step-father's surname.

Dia Mirza began her career as a marketing executive for a media firm, Neeraj's Multi-media Studio, while still in college. Simultaneously, she ventured into the world of modeling, taking part in both print and TV commercials for renowned brands like Lipton, Wall's ice cream, Emami, and numerous others.

She won the title of Miss Asia Pacific International in 2000 after being crowned Femina Miss India Asia Pacific 2000. She made her acting debut with the Hindi film Rehnaa Hai Terre Dil Mein (2001). She subsequently featured in films including Dus (2005), Lage Raho Munna Bhai (2006), Honeymoon Travels Pvt. Ltd. (2007), and Sanju (2018).

Dia Mirza has appeared in several memorable films, including the blockbuster Lage Raho Munna Bhai (2006), Parineeta (2005), Honeymoon Travels Pvt. Ltd. (2007), Shootout at Lokhandwala (2007), Kurbaan (2009), Dus Kahaniyaan (2007), Tehzeeb (2003), Sanju (2018), Thappad (2020), and many more.

Dia Mirza has received several awards for her work in the film industry. She won the IIFA Award for Outstanding Contribution to Environment in 2012 and the Bollywood Movie Award for Best Female Debut in 2002. She also received the Great Women Achiever Award for Beauty in 2005, the Green Globe Honor for Extraordinary Work by a Public Figure in 2011, and the Women’s Achievement Award in 2011. In 2022, she was awarded the Mother Teresa Memorial Award for her notable efforts in leading pivotal environmental campaigns across India.

Dia Mirza leads a disciplined lifestyle. She believes in a holistic approach, focusing not only on physical fitness but also on mental well-being. She incorporates yoga and meditation into her routine to achieve this balance. Adequate sleep and hydration are also priorities for her. To stay fit, Dia engages in yoga, stretching, and breathwork at least three to four days a week.

Dia Mirza was previously married to Sahil Sangha, with whom she co-owned a production house, Born Free Entertainment. Their first film, Love Breakups Zindagi, was released on October 7, 2011. After their divorce, she married Mumbai-based businessman Vaibhav Rekhi in an intimate ceremony on February 15, 2021. The couple welcomed their son, Avyaan Azad Rekhi, in May 2021.