Kumar's first published story was in 1968^[2] or 1969,^[3] in the college magazine of Government Arts College, Coimbatore, where he earned a degree in botany.^[4] He has attributed this to a prank by another student, who used Kumar's name when volunteering to submit a story for the magazine;^[2] when his professor refused to allow Kumar to back out,^[5] "the next day"^[2] he "reluctantly" submitted "Vaazhndhu Kaatuvom", a love story.^[5]

Later that year, he submitted the crime story "Unnai Vidamaatten" to a short story contest in Malai Murasu; this was the first story for which he was paid.^[5]

In 1977, his work began appearing in Kumudam, starting with the short story "Idhu Nyayama".^[5]

His first novel, Vaadagaiku Oru Uyir,^[5] was published in 1980.^[1] He subsequently told of how the editor of Kumudam had "seen a porter on a platform at Egmore Railway Station engrossed in one of [Kumar's] stories. The porter had also forgone customers just to finish the story. It was then that [the editor] decided to make [Kumar] write a novel."^[3]

In 1986, his publisher asked him if he could produce a novel a month; as a result, he became a full-time writer.^[5]

As of 2019, Kumar has written over 1500 novels; his son, for whom digitizing the novels into e-books is a full-time profession, has been able to locate "around 1,000" of them.^[6] He has also written over 2000 short stories, and scripts for over 250 television series,^[1] as well as the 2015 film Sandamarutham.^[7]

In 2019, he announced that he was negotiating with Sathya Jyothi Films regarding adaptations of his work on Amazon Prime.^[6