She did her schooling from different schools, which include Maharani Gayatri Devi Girls Public School in Jaipur followed by Mater Dei Convent School in New Delhi. When she was 14, she lost her father who was a judge in high court in New Delhi. Later, she was brought up by her elder brother who is also a lawyer and a sitting judge of Delhi High Court. She went to Sriram College to complete her graduation in Mathematics followed by doing her post graduation in marketing and then shifted to Mumbai to pick up a corporate job in KLM.
Sandhya Mridul started her career working as a marketing executive in Mumbai and soon got into a popular TV serial called Swabimaan. Soon, she got another set of serials including Banegi Apni Baat, Hu Ba Hu and Koshish. She then did a number of TV serials including Aashirwad, and Hamen Jahan Pyar Mile till she got her first break in Bollywood with the film of Yash Raj Films called Saathiya in 2002. The film was a bit hit and gave her recognition over the silver screen. She was then seen in a number of movies, which include Extraa Innings, Katha, Page 3, Socha Na Tha, Kuch Meetha Ho Jaye, Force, That Day After Every Day and Ragini MMS 2.
For her performance in Page 3, she was nominated for Best Actress at several award functions and also fetched one at BFJA Awards.