His grandfather is M. Karunanidhi, the Ex-Chief Minister of Tamil Nadu. His father is M. K. Stalin, the Ex-Deputy Chief Minister of Tamil Nadu. He is married to Kiruthiga Udhayanidhi, head of Inbox 1305, a magazine.
His debut film as a producer was Kuruvi,starring Vijay and Trisha Krishnan. His next venture was Aadhavan, which was released on Deepavali 2009. His third production, Kamal Haasan's Manmadan Ambu, which was released on 23 December 2010. He also produced Ezham Arivu starring Surya Sivakumar. He also worked as a distributor, with his first one being Gautham Menon's Vinnaithaandi Varuvaayaa. He then released the movies Madrasapattinam, Boss Engira Bhaskaran and Mynaa in 2010.
In 2012, Udhayanidhi debuted as actor in M. Rajesh directed Rom-com Oru Kal Oru Kannadi. His next film was Idhu Kathirvelan Kadhal. He will be seen in Nanbenda with Nayantara directed by Jagadish, Idhayam Murali with Hansika Motwani directed by I. Mueenuddin Ahmed and Thirukumaran's Gethu with Amy Jackson. He has sighed up one more film with Kappal director Karthik G. Krish.