Beginning his film-making career as an assistant to director P. A. Backer, Rajendran made his directorial debut with Venal (1982). From his first film to his latest one, Rathri Mazha (2007), Rajendran has been consistent with the quality of his films, not surrendering to market forces even while using the form and stars of popular cinema.
An active member of the Communist party, Rajendran at times integrates his political orientation into his screen work: his 1985 film Meenamasithile Sooryan was about the anti-feudal upheaval of the 1940s in Kerala from a Communist viewpoint.
Swathi Thirunal (1987), a period film was a biographical work of a 19th-century king of Travancore, better known as a musical composer. While Daivathinte Vikrithikal (1992) was the cinematic adoption of M. Mukundan's novel of the same name, Mazha (2001) was adapted from Madhavikutty's Nashtapetta Neelambhari. One of his latest films, Anyar (2003) deals with the hot topic of communal polarisation in Kerala.