Nikhil was born in Begumpet, Hyderabad. Nikhil did his schooling in Hyderabad Public School (HPS) in Begumpet and St. Patricks' High School, Secunderabad. He was brilliant in school and was a merit student. He studied at the RVR&JC engineering college, Guntur. He started out as an assistant director for the film Hyderabad Nawaabs. He had minor roles in various movies before doing Happy Days, the first movie in Tollywood with an overseas release date earlier than the Indian release. Directed by an Indian national award winner Sekhar Kammula, Nikhil plays one of the 4 male leads in the movie. It was declared a smash hit and gave Nikhil overnight fame. Happy Days was one among the few low budget movies made in 2007 that became commercially successful. His first solo lead movie was Ankit, Pallavi & Friends. He appeared in hit movies like Yuvatha and Veedu Theda which ran for 50 days in Andhra Pradesh and got his major breakthrough in 2013 with the smash hit film Swamy Ra Ra, which was a blockbuster. His next movie, titled Karthikeya, (October 2014) earned him brilliant reviews from critics. The trade pundits declared the movie to have collected over 20 crores at the worldwide box office and certified the film a super hit. His first release in 2015 was Surya vs Surya, which opened to largely positive reviews and was appreciated for its fresh theme and story line. It went on to gross 11 crores in less than two weeks and stood as another success at the box office. His next movie Shankarabaranam opened to mixed reviews but took him to record collections. His next, Ekkadiki Pothavu Chinnavada (2016), turned out to be a blockbuster. Collecting nearly 40 crores during its run, the movie as one of the biggest blockbusters of 2016 for Telugu film industry taking Nikhil to stardom. In 2017 Nikhil once again teamed up with Swamy Ra Ra Director Sudheer Varma for Keshava which is a revenge drama where Nikhil plays the character facing a issue of having heart on right side and a rare problem to it Film released on 19th May 2017 which got positive reviews for Nikhil's performance, musical score, visuals and backdrop of the plot but criticism was for second half was very dull and simple but still movie grossed 20 crores and become another hit for Nikhil. Nikhil Sidharth is in remake of 2016 Kannada campus hit Kirik Party directed by Sharan Koppisetty, screenplay is providing by Sudheer Varma and Dialogues by Chandoo Mondeti and also once again teaming up with Chandoo Mondeti for the sequel to his hit thriller Karthikeya.