Mr Vijayan, 60, was admitted to the hospital since early this month. He was suffering from cardiac and gastrointestinal ailments and breathed his last around 6:45 am.
Uzhavoor Vijayan began his political career through the student wing of the Congress party and has rubbed shoulders with all the leading present generation Congress leaders in Kerala including AK Antony, Oommen Chandy, VM Sudheeran and Ramesh Chennithala.
A hugely popular leader, Mr Vijayan was known for his humour.
Parting ways with the Congress when the party split during the Emergency days, he did not return to the party, even when his illustrious contemporaries like Mr Antony and others returned to the Congress party.
The last rites of Mr Vijayan who is survived by his wife and two daughters, would be performed at his home village - Uzhavoor, on Monday.
Condolences have started to pour in from every political party and leader, as Mr Vijayan had travelled along with both the traditional rival fronts in Kerala in his political career that spanned four decades.