Sandhya was an ordinary school going shy girl until she starred in the critically acclaimed Tamil love story Kaadhal. Initially, this role was offered to Gopika, also a malayalam actress. Due to date problems, this role went on to Sandhya. She was studying in vidyodaya school and her father used to drop her and pick her up at school daily. It was on one such day that she was spotted by director film director Balaji Sakthivel and was offered the female lead role in Kaadhal. She planned to do the Visual Communications course after her plus two. However, due to her rising fame, especially after the super-hit Dishyum, her second Tamil film, she had to discontinue her studies before even passing her 10th standard.
After Kaadhal, for which she won the best Filmfare South actress of 2004, she took up a Malayalam film titled Alice in Wonderland. Then came the musical romance Dishyum with Jeeva.
She was also a part of Mani Ratnam's stage show, Netru, Indru, Naalai. In her third Tamil film, Vallavan, she had only a small role, and the film had only modest box office success.
She also acted in Koodal Nagar with her former co-star Bharath and a Selvaraghavan film. She is getting ready to indulge in some playback singing for her new Tamil film Manjal Veiyil. 
She was approached for the voice-over for Shriya's character in Sivaji but at the last minute Shankar preferred actress Kanika's voice
Alice in Wonderland Alice Malayalam
Koodal Nagar Tamizhselvi Tamil
Kannamoochi Yenada Devasena Tamil
Cycle Meenkashi Malayalam
Thoondil Anjali Tamil
Velli Thirai Sandhya Tamil
Manjal Veiyil Tamil
Mahesh, Saranya Matrum Palar Saranya Tamil
D-17 Susanna Malayalam
Nootrukku Nooru Tamil