Geethu Mohandas started her film career as a child artist with Mohanlal starrer Onnu Mudhal Poojyam Vare, for which she won the Kerala State Award for Best Child Artiste in 1986. This five-year-old child captured the hearts of Malayalam filmgoers as a fatherless child who discovers a father in an anonymous telephone caller.
Later, Geethu Mohandas debuted in Tamil with the title role in En Bommakutty Ammavukku, a remake of director Fazil's Malayalam super hit Ente Maamaattykutty Ammakku (1983). In the Tamil version, Geethu was cast in the role of Baby Shalini in the original; the film went on to become a top grosser in Tamil. In 2003, Geethu came as a heroine in Tamil with Nala Damayanthi opposite Madhavan.
Geetu is one of those rare intellectually ambitious female actors who consciously avoided being cast as a just another beautiful female lead. Instead, right from the beginning of her career, she has accepted the out-of-ordinary and more challenging roles, which a young female actor would normally prefer to refuse. In 2004, she won the Kerala State Film Award for Best Actress for Syamaprasad's Akale and Pradeep Nair's Oridam.