Kamaraj was born on 15 July 1903 to Kumarasamy Nadar and Sivagami Ammal at Virudhunagar in Tamil Nadu. His name was originally Kamatchi, but later changed to Kamarajar. His father Kumarasamy was a merchant. In 1907, four years after the birth of Kamaraj, his sister Nagammal was born. At age 5 (1907), Kamaraj was admitted to a traditional school and in 1908 he was admitted to Yenadhi Narayana Vidhya Salai. In 1909 Kamaraj was admitted in Virudupatti High School. Kamaraj's father died when he was six years old and his mother was forced to support her family. In 1914 Kamaraj dropped out of school to support his family.
As Chief Minister, Kamaraj removed the family vocation based Hereditary Education Policy introduced by Rajaji. The State made immense strides in education and trade. New schools were opened, so that poor rural students had to walk no more than three kilometers to their nearest school. Better facilities were added to existing ones. No village remained without a primary school and no panchayat without a high school. Kamaraj strove to eradicate illiteracy by introducing free and compulsory education up to the eleventh standard. He introduced the Midday Meal Scheme to provide at least one meal per day to the lakhs of poor school children ((The Mid-day Meal Scheme, was first introduced in 1920 by the Madras Corporation with the approval of the legislative council, as a breakfast scheme in a corporation school at Thousand Lights, Madras for the first time in the world)) Later it was expanded to four more schools. This was the precursor to the free noon meal schemes introduced by K. Kamaraj in 1960's and expanded by M. G. Ramachandran in the 1980s.. He introduced free school uniforms to weed out caste, creed and class distinctions among young minds.
He worked in his uncle's provision shop and during this time he started joining processions and attending public meetings about the Indian Home Rule Movement. Kamaraj developed an interest in prevailing political conditions by reading newspapers daily. The Jallianwala Bagh massacre was the decisive turning point in his life, and at this point he decided his aim was to fight for national freedom and to bring an end to foreign rule. In 1920, at the age of 18, he became active as a political worker and joined Congress as a full-time worker. In 1921 Kamaraj was organising public meetings at Virudhunagar for Congress Leaders. He was eager to meet Gandhi, and when Gandhi visited Madurai on 21 September 1921 Kamaraj attended Gandhi's public meeting and met him for the first time in person. He visited villages carrying Congress propaganda.
In 1922 Congress was boycotting the visit of the Prince of Wales as part of the Non-Cooperation Movement. He came to Madras and took part in this event. In 1923–25 Kamaraj participated in the Nagpur Flag Satyagraha. In 1927, Kamaraj started the Sword Satyagraha in Madras and was chosen to lead the Neil Statue Satyagraha, but this was given up later in view of the Simon Commission boycott.
Kamaraj was jailed in June 1930 for two years for participation in the "Salt Satyagraha". led by Rajagopalachari at Vedaranyam; he was released early in 1931 in consequence of the Gandhi-Irwin Pact before he could serve his full term of imprisonment. In 1932, Section 144 was imposed in Madras prohibiting the holding of meetings and organisation of processions against the arrest of Gandhi in Bombay. In Virdhunagar, under Kamaraj's leadership, processions and demonstrations happened every day. Kamaraj was arrested again in January 1932 and sentenced to one year's imprisonment. In 1933 Kamaraj was falsely implicated in the Virudhunagar bomb case. Varadarajulu Naidu and George Joseph argued on Kamaraj's behalf and proved the charges to be baseless. At the age of 34, Kamaraj entered the Assembly winning the Sattur seat in the 1937 election.
Kamaraj was conducting a vigorous campaign throughout the state asking people not to contribute to war funds when Sir Arthur Hope, the Madras Governor, was collecting contributions to fund for the Second World War. In December 1940 he was arrested again at Guntur, under the Defence of India rules for speeches opposing contributions to the war fund, and sent to Vellore Central Prison while he was on his way to Wardha to get Gandhi's approval for a list of Satyagrahis. While in jail, he was elected as Municipal Councillor of Virudhunagar. He was released nine months later in November 1941 and resigned from this post as he thought he had greater responsibility for the nation. His principle was "One should not accept any post to which one could not do full justice".
In 1942, Kamaraj attended the All-India Congress Committee in Bombay and returned to spread propaganda material for the Quit India Movement. The police issued orders to all the Leaders who attended this Bombay session. Kamaraj did not want to get arrested before he took the message to all district and local Leaders. He decided not to go to Madras and decided to cut short his trip; he saw a large number of policemen waiting for the arrest of Congress Leaders in Arakonam but managed to escape from the police and went to Ranipet, Tanjore, Trichy and Madurai to inform local Leaders about the programme. He reached Virdhunagar after finishing his work and sent a message to the local police that he was ready to be arrested. He was arrested in August 1942. He was under detention for three years and was released in June 1945. This was his last prison term. Kamaraj was imprisoned six times by the British for his pro-Independence activities, accumulating more than 3,000 days in jail.
Kamaraj's council of ministers during his first tenure as Chief Minister (13 April 1954 – 31 March 1957):
Kamaraj remained Chief Minister for three consecutive terms, winning elections in 1957 and 1962. Kamaraj noticed that the Congress party was slowly losing its vigour.
During the British regime the education rate was only 7 per cent. But after Kamaraj's reforms it reached 37% . Apart from increasing the number of schools, steps were taken to improve standards of education. To improve standards, the number of working days was increased from 180 to 200; unnecessary holidays were reduced; and syllabuses were prepared to give opportunity to various abilities. Kamaraj and Bishnuram Medhi (Governor) took efforts to establish IIT Madras in 1959.
Kamaraj's council of ministers during his third tenure as Chief Minister (3 March 1962 – 2 October 1963):
In 1963 he suggested to Nehru that senior Congress Leaders should leave ministerial posts to take up organisational work. This suggestion came to be known as the Kamaraj Plan, which was designed primarily to dispel from the minds of Congressmen the lure of power, creating in its place a dedicated attachment to the objectives and policies of the organisation. Six Union Ministers and six Chief Ministers including Lal Bahadur Shastri, Jagjivan Ram, Morarji Desai, Biju Patnaik and S.K. Patil followed suit and resigned from their posts. Impressed by Kamaraj's achievements and acumen, Prime Minister Jawaharlal Nehru felt that his services were needed more at the national level. In a swift move he brought Kamaraj to Delhi as the President of the Indian National Congress. Nehru realized that in addition to wide learning and vision, Kamaraj possessed enormous Common sense and pragmatism. Kamaraj was elected President, Indian National Congress, on 9 October 1963.
After Nehru's death in 1964, Kamaraj successfully navigated the party through turbulent times. As President of the INC, he refused to become the next prime minister himself and was instrumental in bringing to power two Prime Ministers, Lal Bahadur Shastri in 1964 and Nehru's daughter Indira Gandhi in 1966. For this role, he was widely acclaimed as the "kingmaker" during the 1960s.
When the Congress split in 1969, Kamaraj became the leader of the Indian National Congress (Organisation) (INC(O)) in Tamil Nadu. The party failed poorly in the 1971 elections amid allegations of fraud by the opposition parties. He remained as the leader of INC(O) until his death in 1975.
Kamaraj died at his home, on Gandhi Jayanti day (2 October 1975), which also the 12th anniversary of his resignation. He was aged 72 and died in his sleep.
Kamaraj was awarded India's highest civilian honour, the Bharat Ratna, posthumously in 1976. He is widely acknowledged as "Kalvi Thanthai" (Father of Education) in Tamil Nadu. The domestic terminal of the Chennai airport is named "Kamaraj Terminal". Chennai's beach road is named "Kamarajar Salai", Bangalore's North Parade Road and Parliament road in New Delhi as "K. Kamaraj Road" and the Madurai Kamaraj University in his honour.in 2003 the government of India in his birthday commemorative coin was released.
In 2004 a Tamil-language film titled Kamaraj was made based on the life history of Kamaraj. The English version of the film was released on DVD in 2007.