His first intention was to be a doctor, but finally he decided to be an actor, like his father T. Thiagarajan, also producer and film director (later, Prashanth's manager, too). He debuted in the film "Vaikasi Pranthachu" (1990) at the age of 17. His very first hit was "Thief, Thief" (1993), confirmed finally in 1998 with "Jeans" directed by Shankar.