Born on 23rd May, 1945 in a small village, Muthukulam in Alappuzha district in Kerala, as the sixth son of Shri. Thundathil Anantha Padmanabha Pillai and Smt. Njavarakkal Devaki Amma. After his schooling at Muthukulam Boys High School, in 1959 he joined for Pre-University at Mahathma Gandhi College Thiruvananthapuram. After that he joined for Degree in University College Thiruvananthapuram opting Chemistry as his main subject and became a graduate in 1963. After his graduation, for nearly two and a half years he stayed in his home at Muthukulam and learned Sanskrit from the great Sanskrit Pandit shri Cheppad Achyutha Warrier. 

On April 26th 1965, he joined Trissur All India Radio as Programme Announcer. During this period, he started writing short stories in magazines like Mathrubhumi, and Kaumudi. On 24th March 1970, he married Radhalakshmy who worked with him in Thrissur AIR, at Guruvayoor temple. In 1968, after getting transferred to AIR, Thiruvananthapuram they stayed at Poojapura in Thiruvananthapuram.

During this period itself he became popular among literary figures. In 1972, he got that year's Kerala Sahithya Academy Award for his very first novel Nakshathrangale Kaval. In 1974, he entered the world of cinema by writing script for the film Prayanam, which was directed by Shri. Bharathan, which was the first film of Bharathan also. After that he has written scripts for many directors like IV Sasi, Mohan and K G George. Padmarajan-Bharathan tie was a big success at that time. They have launched many hit films like Thakara, Lorry, Rathinirvedam etc. Some of his short stories have been remade in other Indian languages like Tamil, Telugu and Hindi.

His first venture as a film director was in 1978 by directing the film Peruvazhiyambalam scripted by Padmarajan himself, which bagged that year's National award for Best Regional Film and State Awards for Second Best Film and best Script writer. Following this the film Oridathoru Phayavan, written and directed by Padmarajan, which was released in 1980 got selected in the Kulalampur film festival that year and bagged awards for Best Film and Best Script writer.
As he became too busy in the film world, he was not able to go to AIR and so in 1986, he took voluntary retirement from there.

After that he was fully involved in the making films. 

Spending his whole life time in Literature and Cinema, he left this world on 23rd January, 1991 midnight in a hotel room (Paramount Towers) in Kozhikkode in a silent heart attack.