Early work

During his studies in the schools and colleges, he had acted in dramas of the Shakespearean genre. Later on, Kunchacko of Udaya Studios, Alleppey, identified his talent and gave him a role to act in his film Visappinte Vili in which he acted as villain against the Evergreen Hero, Prem Nazir. This happened to be the first film in Malayalam in which a villain fights with the hero without a dupe and that role was performed with aplomb by Sasikumar. Subsequently, in addition to acting in several films produced by Udaya Studios he worked as the assistant director of Kunchacko in those films.

Later on, he joined Merryland Studios, owned by the veteran director-producer P. Subramaniam. It was under his tutelage that Sasikumar was transformed into a great director. While in Merryland he worked with many renowned actors of that time, including T. K. Balachandran, Prem Nazir and Thikkurissy Sukumaran Nair. He worked as associate director to P. Subramaniam in addition to acting in some roles himself. Sasikumar still considers P.Subramanyam as a fatherly icon who had showered upon him fatherly affection and regards during his tenure at Merryland. The first independent film directed by Sasikumar was a documentary, namely ONAKKAZHCHA for Fertilisers and Chemicals Travancore Limited (FACT) regarding the use and effectiveness of fertilizers in agriculture.

Peak years

Following the advice of his friend Prem Nazir, Sasikumar went to Chennai in the 1960s. He directed Thommante Makkal and Porter Kunjali for Thomas Pictures in 1965. He also directed, along with P. A. Thomas, the movie Kudumbini (1964) for Thomas Pictures, which received a Certificate of Merit at the annual National Film Awards. Subsequently, he directed an art film, Kavalam Chundan, which was a flop. As a result, a dejected Sasikumar decided to give up film direction and return to Kerala to join his father's oil mill business. It was Prem Nazir who encouraged him to return to Chennai where he directed the commercial film Jeevitha Yaathra which became a major hit. After this, Sasikumar understood that he could not make an art film like Kavalam Chundan with producers' money. But after his change of style from art to commercial films he never looked back.

Along with Prem Nazir he helped many producers who had lost their land and jewellery through movie production. Sathyan, Prem Nazir, Adoor Bhasi, S. P. Pillai, Madhu, Jose Prakash, Sheela, Vijayasree, K.R.Vijaya, Sharada, Vidhubala, Lakshmi, Sreelatha, Jayabharathi, Sreevidya, Nanditha Bose, Unni Mary, Kamal Haasan, Mammootty, Sukumaran, Soman, Ravikumar, Jayan, Vincent, Sobhana, Shankar, Mohanlal and Suresh Gopi all acted in his films. Kaviyoor Ponnamma, who had acted in the role of a mother in his old movie Thommante Makkal which had a story with a Christian background acted in the same movie, remade with a Hindu background and retitled Swanthamevide Banthamevide taking the same role after 25 years. Some years later, Sasikumar remade the same movie under the title "Raja Vazhcha". It was Sasikumar who introduced a new sophisticated villain to the Malayalam film world in the form of "Silver Head" enacted by Jose Prakash in Love in Kerala (1968). During his long career in film he has directed more than 140 films in Malayalam and one film in Tamil. The trio consisting of Sasikumar, Sreekumaran Thampi and M.K Arjunan was the rage of the period 1969–1980.

Acting

Sasikumar acted in small roles in films like Thiramala, Sreerama Pattabhishekam, Velakkaran, Thommante Makkal, Seetha, Snehadeepam, Umma, Bhakta Kuchela, Snapaka Yohannan, Kattumaina, Visappinte Vili, Oral Koodi Kallanayi etc. He has also written the story, cinema script and dialogue for many of his films.