Rishi was born in Bangalore, Karnataka, India, and brought up in Mysore, Karnataka. His father Sri K C Nagaraj was a bank official working in Kaveri Grameena Bank and his mother Anala Nagaraj is a home maker. Early name is Monish Nagaraj. He did his schooling from St Joseph's Primary School, Mysore and Pre - University course from Marimallappa 's College, Mysore. He went on to attend Sri Jayachamarajendra College of Engineering, Mysore, pursuing a Bachelor’s in Civil Engineering.

During his engineering days, Rishi developed a keen interest in acting and started performing with various amateur theatre groups in Mysore. He was in charge of the dramatics team at his college and also worked as a Radio Jockey outside.