Daughter of noted Kathakali Artiste Shri. Kalamandalam Karunakaran, better known as Vaikkom Karunakaran, Renjini was trained from a very young age by her by her father. After her arangettam when she was seven, her father began training her rigorously in the same style that he was trained in at his alma mater Kalamandalam by his gurus. Later she participated and won prizes in various competitions including the prestigious Kerala State youth festivals in both school & university level. She later joined the Tripunithura Kathakali Kendram Ladies Troupe an all women Kathakali troupe at Tripunithura. She has moved on to giving individual performances and conducting and organizing Kathakali Performances for different organizations as well as teaching Kathakali for students. Her Gurus include Kalamandalam Ramankutty Nair, Kalamandalam Sreekumar, FACT Mohanan, & FACT Padmanabhanan.

Renjini completed her L.L.M. (Masters in Law) from the Ernakulam Law College, never once losing touch with Kathakali. She loves a challenge. Her favourite is the Kathivesham, which is more challenging and more demanding. Of the villains ‘Ravana’ is her hero. She has successfully portrayed Ravana in "Ravanolbhavam" and "Bali Vijayam" as well as Narakasuran in "Narakasuravadham" in the process becoming the first woman to enact these roles on stage.

Presently Renjini performs all over India donning various major roles.