The history of independent India or history of Republic of India began when the country became an independent sovereign state within the British Commonwealth on 15 August 1947. Direct administration by the British, which began in 1858, affected a political and economic unification of the subcontinent. When British rule came to an end in 1947, the subcontinent was partitioned along religious lines into two separate countries—India, with a majority of Hindus, and Pakistan, with a majority of Muslims. Concurrently the Muslim-majority northwest and east of British India was separated into the Dominion of Pakistan, by the Partition of India. The partition led to a population transfer of more than 10 million people between India and Pakistan and the death of about one million people. Indian National Congress leader Jawaharlal Nehru became the first Prime Minister of India, but the leader most associated with the independence struggle, Mahatma Gandhi, accepted no office. The constitution adopted in 1950 made India a democratic republic with Westminster style parliamentary system of government, both at federal and state level respectively. The democracy has been sustained since then. India's sustained democratic freedoms are unique among the world's newly independent states, despite its history being perforated by several crises and recent worries of democratic backsliding under the premiership of Narendra Modi.

The country has faced religious violence, corruption, poverty, unemployment, language conflicts, naxalism, terrorism, separatist insurgencies in North East India and gender-based violence. India has unresolved territorial disputes over Kashmir and Arunachal Pradesh with China which escalated into a war in 1962 and 1967, Kashmir with Pakistan which resulted in wars in 1947–1948, 1965, 1971 and 1999 and Kalapani with Nepal. India was neutral in the Cold War, and was a leader in the Non-Aligned Movement. However, it made a loose alliance with the Soviet Union from 1971, when Pakistan was allied with the United States and the People's Republic of China.

India is a nuclear-weapon state, having conducted its first nuclear test in 1974, followed by another five tests in 1998. From the 1950s to the 1980s, India followed socialist-inspired policies. The economy was influenced by extensive regulation, protectionism and public ownership, leading to pervasive corruption and slow economic growth. Since 1991, India has pursued more economic liberalisation. Today, India is the third largest and one of the fastest-growing economies in the world.

From being a relatively struggling country in its formative years, the Republic of India has emerged as a fast growing G20 major economy. India has sometimes been referred to as a great power and a potential superpower given its large and growing economy, military and population.

Independent India's first years were marked with turbulent events—a massive exchange of population with Pakistan, the Indo-Pakistani War of 1947 and the integration of over 500 princely states to form a united nation. Vallabhbhai Patel, Jawaharlal Nehru and Mahatma Gandhi also ensured that the constitution of independent India would be secular.

The partition of India was outlined in the Indian Independence Act 1947. It led to the dissolution of the British Raj in South Asia and the creation of two independent dominions: India and Pakistan. The change of political borders notably included the division of two provinces of British India, Bengal and Punjab. The majority Muslim districts in these provinces were awarded to Pakistan and the majority non-Muslim to India. The other assets that were divided included the British Indian Army, the Royal Indian Navy, the Royal Indian Air Force, the Indian Civil Service, the railways, and the central treasury. Self-governing independent Pakistan and India legally came into existence at midnight on 14 and 15 August 1947 respectively.

The partition caused large-scale loss of life and an unprecedented migration between the two dominions. Among refugees who survived, it solidified the belief that safety lay among co-religionists. In the instance of Pakistan, it made palpable a hitherto only-imagined refuge for the Muslims of British India. The migrations took place hastily and with little warning. It is thought that between 14 million and 18 million people moved, and perhaps more. Excess mortality during the period of the partition is usually estimated to have been around one million. The violent nature of the partition created an atmosphere of hostility and suspicion between India and Pakistan that affects their relationship to this day.

An estimated 3.5 million Hindus and Sikhs living in West Punjab, North-West Frontier Province, Baluchistan, East Bengal and Sind migrated to India in fear of domination and suppression in Muslim Pakistan. Communal violence killed an estimated one million Hindus, Muslims and Sikhs, and gravely destabilised both dominions along their Punjab and Bengal boundaries, and the cities of Calcutta, Delhi and Lahore. The violence was stopped by early September owing to the co-operative efforts of both Indian and Pakistani leaders, and especially due to the efforts of Mohandas Gandhi, the leader of the Indian freedom struggle, who undertook a fast-unto-death in Calcutta and later in Delhi to calm people and emphasise peace despite the threat to his life. Both governments constructed large relief camps for incoming and leaving refugees, and the Indian Army was mobilised to provide humanitarian assistance on a massive scale.