After the success of Pariyerum Perumal, Dhanush managed to watch the film and appreciated Mari Selvaraj for his exceptional work. He appreciated Mari Selvraj and signed a film with him. The film was titled Karnan and went on floors in 2019. Due to the novel coronavirus pandemic, the film's shooting had to be postponed. In December 2020, Dhanush and director Mari Selvaraj wrapped up the film's shoot. On January 31, the makers of Karnan announced the film's release date with a new teaser and brand new posters.
Karnan will release in theatres in April 2021. Dhanush appreciated producer Kalaipuli S Thanu for taking the bold decision to release in theatres. In a statement, he wrote, "Karnan releases on April 2021 in theatres. A much needed encouraging news at the right time. Thank you Thanu sir for thinking of the theatre owners, distributors, exhibitors and everybody who's livelihood is dependant on films and theatres, even though you had other options. A big thank you on behalf of my fans as this means a lot to them." Karnan also features Lakshmi Priya, Lal and Yogi Babu in pivotal roles. The film has music composed by Santhosh Narayanan.