Pooja's mother Sandhya is a Sri Lankan Sinhalese and her father H.R.Umashankar is an Indian Kannadiga Brahmin from Sringeri in Chikmagalur district, Karnataka. Uma Shankar was at Valparai working with Hindustan Unilever Limited as a manager. After she did her pre-schooling in Sri Lanka, she came to India and went to Poornapragnya in Aldur, Chikmagalur and then to Nirmala Convent in Mysore. Later she continued her education at Baldwin's Girls High school in Bangalore and did graduation (B.Com) and Post Graduation (MBA) at Mount Carmel College, Bangalore.
Pooja made her acting debut in Tamil film industry with Ullam Ketkumae, but unfortunately massive delay, it meant her second film. The film Jay Jay was directed by Saran, which became the first official release. She received favorable reviews for her performance in Jay Jay. She next played the romantic interest of Ajith Kumar in another Saran film, Attahasam, which, in spite of mixed critical response, went on to become a financial success. Pooja's subsequent release happened to be Ullam Ketkumae that featured her in one of the five leading roles, the film fetched positive remarks and emerged as a sleeper hit. She went to appear in commercial Tamil films such as Thambi and Pori. In 2007, Pooja also appeared in a Malayalam film,Panthaya Kozhi, before landing the lead female role in Bala's Naan Kadavul. Following Naan Kadavul, Pooja went on a sabbatical, appeared just in cameo roles in TN-07 AL 4777, Drohi and the Telugu film Orange. She became a sensation in Sri Lankan film industry and a household name after the success of Anjalika and Asai Man Piyambanna. She then on went to appear in several blockbusters in Sinhala cinema and rose to high popularity. Her big budget film Kusa Pabha released in early 2012 and became the highest grosser ever in the history of Sri Lankan film industry. Critics praised Pooja for her role of Pabawathi. Pooja has been a part of a short film titled Mirage. The film was screened in various short film festivals in India and The West Midlands International film festival in UK, fetching accolades for the film and Pooja's performance. When she was shooting for Mirage, she also starred in Smoking kills a short film made by University students as a student welfare initiative.