A voracious reader and prolific author, he went on to write screenplays and dialogues for over 50 movies, prominent among them being "Parasakthi" starring Sivaji Ganesan in 1952, and scripted the story for several of them.
Age did not wither his pithy prose as Karunanidhi wrote his last script at the age of 90 for a television serial based on the 11th century reformist Hindu saint Ramanuja, who strove for an egalitarian society.
Scripting dialogues for the television soap based on the Vaishnavite saint in 2015, Karunanidhi had praised Ramunja for throwing his weight behind the oppressed and backward classes.
Karunanidhi, who passed away yesterday aged 94, took a keen interest in Tamil literature, poetry and drama.
As a teenager, he ran a handwritten magazine "Manava Nesan" in 1941.
In 1947, Karunanidhi wrote the screenplay and dialogue for the blockbuster 'Rajakumari', the debut movie of M G Ramachandran, who later became his arch political rival and founded the AIADMK.
Little did the DMK chief know that his dialogues in 'Parasakthi, which debutant 'Sivaji' Ganesan delivered with panache, would become a big hit and aid in catapulting his political career as well.
'Manohara' (1954), 'Malaikallan' (1954), 'Rangon Radha' (1956) were among the movies in which he was involved as a screenwriter.
In addition to penning dialogues, he had also written stories for movies, including successful films like 'Marudanattu Ilavarasi', 'Mandiri Kumari (both 1950), Tirumbipar (1953) and Arasilangkumari (1961).
'Mani Makudam', 'Marakka Mudiyuma', 'Avan Pithana', 'Pookkari' and 'Needhikku Thandanai' were among his several other movies.
A noted Tamil author, Karunanidhi has over 100 works to his credit, including poems and novels.
His novels include 'Romapuri Pandian', 'Thenpandi Singam', 'Nenjukku Needhi' (his autobiography and commentary on contemporary politics), Sanga Thamizh, Kuraloviam, Ponnar Shankar, Thirukkural Urai.
His stage plays include 'Manimagudam', 'Ore Ratham', 'Thooku Medai,' 'Kagithapoo' and 'Silapathikarum.'