His political rival, Jayalalithaa, bolstered by her allies, has delivered near-record results in the election.
"The people of Tamil Nadu have given me rest," said Mr Karunanidhi after his party and the Congress together won just 32 of the 234 seats at stake.
The last few months have tested Mr Karunanidhi politically and personally. His daughter, Kanimzohi, who is an MP and is reported to be his favourite child, could go to jail tomorrow for allegedly accepting a bribe in the 2G spectrum scam. The man accused of masterminding that scam -A Raja - is a senior Dalit leader of Mr Karunadhi's party, the DMK, and is in jail.
His daughter has been interrogated and summoned to a court in Delhi to explain her links to a 200-crore payment that was allegedly a kickback for Mr Raja and was deposited in a TV channel in which she has a 20% stake. As the investigation by the CBI inched closer to his family, Mr Karunanidhi confronted an aggressive demand by his partner, the Congress, for 63 seats in the state. The DMK first threatened to pull out of the UPA coalition at the centre - a bluff that was called by the Congress, which knew that the 2G scam had left the DMK enervated.
With seat-sharing settled on the terms dictated by the Congress, Mr Karunanidhi, who uses a wheelchair, began an exacting campaign. He addressed rallies, including one with Congress president Sonia Gandhi. He sifted through hundreds of party workers looking for tickets for the elections. He tried to check the public battle that often plays out between his sons, Alagiri and Stalin, who both want to play a bigger role in Tamil Nadu, where Stalin was, till today, the Deputy Chief Minister.
Mr Karunanidhi has been Chief Minister of Tamil Nadu five times. He has also never lost an election personally since 1957, when he entered electoral politics.
Mr Karunanidhi, who was born on June 3, 1924, joined the Tamil film industry in 1950s, writing dialogues and screenplays.Powerful dialogues in his debut movie 'Parasakthi', which starred his friend , the late actor Shivaji Ganesan, catapulted Mr Karunanidhi into the league of hit-makers. He became known for for writing historical and reformist stories which propagated the ideals of the Dravidian movement .
He joined the Justice Party when he was 14 and then moved to the DMK when the party was set up by leaders like C N Annadurai and E V Ramaswamy.
Mr Karunanidhi entered the state assembly in 1957 from Kulithali in the Karur district where he had led an agitation in support of farm workers. He became the Deputy Leader of the Opposition in 1962 and in 1967, was named the Public Works Minister in
the first DMK ministry headed by Mr Annadurai.
After Mr Annadurai died of cancer in 1969, Mr Karunanidhi became Chief Minister.
In 1972, he expelled the powerful treasurer of the party, Tamil film icon M G Ramachandran or MGR, who had accused Mr Karunanidhi and his cabinet of corruption. It was a mistake that would haunt Mr Karunanidhi for years. MGR, who became the Chief Minister in 1977, ensured the DMK was not able to return to power while he was alive. He died in 1987.
In the 1989 Assembly elections, Karunanidhi appealed to voters to end his exile -he compared it to the 14 years that Lord Ram spent away from Ayodhya. He had been in power for just 18 month, when then then Prime Minister S Chandrashekar dismissed his government on the charge that it allowed a free run to the Sri Lankan Tamil militant group LTTE.
In the 1991 Assembly polls, the DMK was defeated. Since then, the state has alternated between Jayalalithaa and him - with each being voted out at the end of their term.