Ramu Sunil was born in Kolazhy, Thrissur district, as the son of Sunil Raj and Kala Raj. He completed his primary education at Chinmaya Vidyalaya, Kolazhy. Having developed a keen interest in cinema since childhood, Ramu Sunil pursued a Bachelor's degree in Visual Communication from VRD College of Science, Coimbatore, after completing his higher secondary education. During his college days, Ramu Sunil used to direct short films. Impressed by his work, his college senior, Abhinav, offered him an opportunity to work as an assistant director on the Tamil-Malayalam bilingual film Samsaram Aarogyathinu Haanikaram, where Abhinav was working as the editor. Thus, in 2013, Ramu Sunil made his entry into the film industry as an assistant director. Following that, he worked as an assistant director on the movie Aaha. He also made his debut as a writer by co-writing the story for the movie Rekhachithram along with director Jofin T. Chacko. Having made several short films, Ramu Sunil won awards at the FEFKA Short Film Festival for his film 18+.