He had played major roles in dramas like Sakhavu, Pazhassi Raja, Soorya Pett, Swathanthryathinte Murivukal, Freedom Road, Samaya theeram, Marupuram and Che Guevera.

He played the lead role for the first time in Beegum Mary Biswas, a drama promoted by Theatre Vision Kerala.

He was actively involved in Kozhikode Chiranthana's Kodeeswaran and Padanilam, KPAC's Innalekalile Aakasam, Thiruvananthapuram Aksharakala's Kottayath Thampuran, Kollam Viswabhavana's Avathara Purushan and Alapuzha Sangha Chithra's Karashaka Rajavu.

[5][6][7] Among the theatre ventures of Santhosh, Pen Nadan (പെൺ നടൻ) won large scale critical acclaim.

Velukutti had metamorphosed into many women characters of legendary poet Kumaran Asan on stage and they include Vasavadatta, Nalini, Seetha, Leela and Mathangi.