He studied in National Boys High School, Kodakara and TTC from District Institute of Education and Training (DIET), Ramavarmapuram, Thrissur.
Nambadan had in public cut the veins on his hand earlier to sabotage the attempts of some rebel members led by the E. John Jacob to split the Kerala Congress.
He had burnt English copies of legislative bills in the Assembly hall and his supporters had to undergo several days of imprisonment for shouting slogans demanding introduction of Malayalam as official language.
In 2004 he was elected to the Lok Sabha from the Mukundapuram constituency, defeating Karunakaran's daughter Padmaja Venugopal by a margin of more than a lakh votes.
He played the late Bengal Chief Minister Jyoti Basu in Shaji N. Karun's documentary film on Communist leader A. K. Gopalan, titled AKG.