He was 74 and had been keeping indifferent health for some time.
Jagannathan had acted in over 170 films.
He started his career with the 'Thanathu Natakavedi,' the theatre movement launched by eminent playwright Kavalam Narayana Panicker, which was the revival of folk traditions on stage in the 1970s.
He appeared in a prominent role in Kavalam's widely acclaimed play "Avanavan Kadamba", directed by late G Aravindan.
Jagannathan made his film debut with Aravindan's "Oridathu."
Even after establishing himself as film actor, he continued to love the stage, especially the troupe of Kavalam.
In recent years, Jagannathan also acted in several tele-serials.