During her school days, Sonia Agarwal got an offer to act in a serial in Zee TV. She then made her film debut with the 2002 Telugu film Nee Premakai, in which she did a small cameo role, after which she acted in a Kannada film Chandu opposite Sudeep.
Subsequently, she stepped into the Tamil film industry, appearing in the drama film Kaadhal Kondein, directed by Selvaraghavan. She was cast opposite Tamil superstar Dhanush and the film was a huge box-office smash. She too received positive reviews from critics and her performance as Divya immediately catapulted her to the limelight and also fetched her several recognition and awards.
Afterwards, she acted alongside popular actors Silambarasan and Vijay in the films Kovil and Madhurey, respectively. In 2004, the controversial Tamil drama film 7G Rainbow Colony, directed by Selvaraghavan again, got released, which went on to become successful at the box office.
She took a break from acting after getting married in 2006. After getting divorced, she made a re-entry, playing a supporting role in the multi-starrer Vaanam, following which she signed up for four projects, three in Tamil and one in Malayalam, in quick succession. Her next releases were Sadhurangam, opposite Srikanth once again, in 2011 and Oru Nadigayin Vakku Moolam in early 2012. Her forthcoming films include Poi Sollathedi and Achchamenn.