Udhayanidhi Stalin completed his schooling at Don Bosco Matriculation Higher Secondary School in Egmore, Chennai, and later graduated with a commerce and visual communications degree from Loyola College in Chennai.

In 2008, Udhayanidhi founded a major production and distribution company Red Giant Movies.

Interestingly, he made his debut as a producer with the film Kuruvi in 2008, which starred Vijay in the lead. Almost two decades later, the two serve as opposition leaders in the Tamil Nadu state government.

Years after working behind the scenes, he made his acting debut in the romantic comedy Oru Kal Oru Kannadi in 2012.

Udhayanidhi formally entered active electoral politics in 2019, taking charge of the DMK Youth Wing.

He quietly managed grassroots election campaigns for his father, MK Stalin and grandfather, M. Karunanidhi, for over a decade.

In 2023, he made his final film appearance in Maamannan. Later in July that year, he announced his resignation from Red Giant Movies due to his failed reception as an actor.

In September 2024, Udhayanidhi was appointed as the deputy chief minister of Tamil Nadu, making him the third person and the youngest to hold the office.

Udhayanidhi describes himself as an atheist and has often spoken against Sanatana Dharma, even likening it to diseases like malaria and dengue.

While addressing a rally regarding the Cauvery water dispute in Thanjavur on August 3, 2026, he was speaking about Tamil Nadu CM Vijay, when he made an obscene remark about Trisha, and later clarified he was talking about Cauvery.

Consequently, a complaint was filed against him by the TVK, which led to the leader of the opposition being arrested from his residence on Tuesday morning.