At the age of six, Shanmugam joined the troupe of the legendary Sankaradas Swamigal, considered the father of Tamil theatre.

In later years, he went on to do the title role in the play ‘Avvaiyar’, portraying the famous Tamil woman poet.

His self-effacing autobiography Yenathu Nataka Vaazhkai, gives a panoramic view of the theatre from the beginning of the 20th century, the personalities involved in it, the plight of boys who were inducted into these troupes by their parent out of poverty, the social status of the actors and importantly the uncertain financial condition.

Actors such as N. S. Krishnan, K. R. Ramasamy, S. S. Rajendran, M. N. Rajam, director A. P. Nagarajan and one of the outstanding Carnatic vocalists T. M. Thiagarajan were some names associated with the TKS Brothers troupe.

They used many of the songs of late communist leader P. Jeevanandham in their plays and it was Shanmugam who wrote a foreword for Annadurai's first novel, Kumasthavin Magal.