Ramu Kariat is regarged as one of the foremost film directors who brought Malayalam Cinema in focus to the rest of the country.

He was born in Engandiyur in Trichur District in Kerala in a family of farmers. He started writing poetry and prose while still a teenager for the popular weekly Matrubhoomi. He entered cinema assisting Vimal Kumar and PRS Pillai on the film, Thiramala (1953), a film about separated lovers. The lyrics for the film were written by P Bhaskaran with whom Kariat co-directed his first feature film, Neelakuyil (1954).

Neelakuyil set a trend for realistic melodrama in Malayalam Cinema. The film, with a story by well-known writer Uroob, was a musical success, representing the best work of singer Kozhikode Abdul Qadir. In the film, a Harijan girl, Neeli, is found dead with her illegitimate child. The child is then adopted by the postman, a high caste Hindu, much to the chargin of the rest of the village. Ultimately the child's real father, a high caste teacher (Sathyan) with a barren wife, acknowledges that he is the father of the child. The film is regarded as the first major breakthrough in Malayalam cinema.

Kariat's following film Minnaminungu (1957) however was not as successful. The film was a melodrama about a young woman, Ammini who becomes an orphan due to a doctor's negligence. She becomes a maid and a surrogate mother in the new doctor's household but the doctor's wife, feeling insecure, has her sacked. But finally the misunderstandings are all cleared with the doctor's family happily accepting Ammini. The doctor is then transferred elsewhere. Though the film was a failure, Kariat was still praised for his adept handling of a virtual unknown cast.

Kariat's earlier work is in context to the cutural renaissance in Kerala due to the Kerala Peoples' Arts Club. He opened up new avenues for Malayalam Cinema with works about a newly discovered community sense through subjects based in villages or among the fisherfolk. He also got several well-known writers in Kerala like Gyanpith Award Winner Thakazhi Sivasankara Pillai, Uroob, playwrights Thoppil Bhasi, KT Mohammed and SL Puram Sadanandan into Malayam filmdom.

Mudiyanaya Putram (1961) was responsible fior shaping actor Sathyan's classic persona as the brooding and remote macho outlaw. The film looks at the irresponsibility of a self-centred man who deliberately gets into ani-social behaviour before being humanised due to the love of a young untouchable girl (Kumari) he had molested and by the warmth of a group of workers. The film is ana daptation of a Thoppil Basi play and was actively supported by the Kerala CPI with many of its members acting in the film. People still recall the remarkable opening scene where Sathyan lights a cigarette in darkness and then molests the harijan girl.

Kariat then made Moodupadam (1963), a film that looks at Hindu-Christian and Hindu-Muslim relations. The film realizes that marital relations between the former seem possible but sadly not between the latter as ultimately the Hindu boy, Appu, gets his sister married to a Chritian boy but has to arrage the marriage of his beloved, Ameena, to a Muslim soldier.

But if one film immortalized Kariat, it was undoubtedly Chemmeen (1965), a tragic story on forbidden love between a Hindu fisherwoman, Karuthamma (Sheela),and a Muslim trader, Pareekutty (Madhu). Chemmeen, the first colour film in Malayalam, is based on a highly acclaimed novel by TS Pillai. Since its initial publication in Malayalam in 1956, the novel has run into several editions in quick succession and is perhaps the most well known literary work in Kerala. It has also been translated in various Indian Languages and also in English, Russian, German, Italian, French, Czech, Spanish and Polish among others. Hence when the film was being made, expectations were sky high. The film, needless to say, firmly delivers with career defining performances by Sheela, Madhu and Sathyan aided by an outstanding musical score by Salil Choudhury. It has subsequently acquired cult status in the history of Malayalam Cinema as it was the first South Indian film to win the coveted President’s Gold Medal for Best film. Malayalam Cinema has never looked back since.

Perhaps Kariat's last film of merit was Ezhu Ratrikal (1968) following Kaladi Gopi's play. The film throws various disparate characters together into a socially ambiguous space as a number of vagabonds and social outcasts take shelter every night in an old, dilapidated house.

Other films directed by Kariat include Abhayam (1970), Maya (1972), Nellu (1974), Dweep (1976) and Ammuvinte Attinkutty (1978). He also directed the the documentaries Bharat Natyam (1956) and Manavallakurchi: My Village (1974).

Kariat also acted in P Bhaskaran's Rarichan Enna Pauran (1956) and produced M Lakshmanan's Tamil film, Kannamma (1972). He had finished shooting for the Telegu film Kondagali when he passed away leaving it unedited. His last film in Malayalam, Karambu, was completed finally by K Vijayan and released in 1984.

Kariat was a member of the CPI and also served as a Kerala MP briefly.