Public Sector Undertakings (PSU) in India are government-owned entities in which at least 51% of stake is under the ownership of the Government of India or state governments. These types of firms can also be a joint venture of multiple PSUs. These entities perform commercial functions on behalf of the government. Depending on the level of government ownership, PSUs are officially classified into two categories: Central Public Sector Undertakings (CPSUs), owned by the central government or other CPSUs; and State Public Sector Undertakings (SPSUs), owned by state governments. CPSU and SPSU is further classified into Strategic Sector and Non-Strategic Sector. Depending on their financial performance and progress, CPSUs are granted the status of Maharatna, Navaratna, and Miniratna (Category I and II).

Following India's independence in 1947, the limited pre-existing industries were insufficient for sustainable economic growth. The Industrial Policy Resolution of 1956, adopted during the Second Five-Year Plan, laid the framework for PSUs. The government initially prioritized strategic sectors, such as communication, irrigation, chemicals, and heavy industries, followed by the nationalisation of corporations. PSUs subsequently expanded into consumer goods production and service areas like contracting, consulting, and transportation. Their goals include increasing exports, reducing imports, fostering infrastructure development, driving economic growth, and generating job opportunities. Each PSU has its own recruitment rules and employment in PSUs is highly sought after in India due to high pay and its job security, with most preferring candidates with a GATE score. These jobs are very well known for very high pay scale compared to other Government jobs such as UPSC, facilities such as bungalow, pensions and other subsidized facility and for also very good planned townships settlement life. A PSU non-executives such as workers have a huge payscale difference compared to private sector.

In 1951, there were five PSUs under the ownership of the government. By March 2021, the number of such government entities had increased to 365. These government entities represented a total investment of about ₹16,410,000,000,000 as of 31 March 2019. Their total paid-up capital as of 31 March 2019 stood at about ₹200.76 lakh crore. CPSEs have earned a revenue of about ₹24,430,000,000,000 + ₹1,000,000,000,000 during the financial year 2018–19.

When India achieved independence in 1947, it was primarily an agrarian entity, with a weak industrial base. There were only eighteen state-owned Indian Ordnance Factories, previously established to reduce the dependency of the British Indian Army on imported arms.

The British Raj had previously elected to leave agricultural production to the Private sector, with tea processing firms, jute mills (such as the Acland Mill), railways, electricity utilities, banks, coal mines, and steel mills being just some of the economic entities largely owned by private individuals like the industrialist Jamsetji Tata. Other entities were listed on the Bombay Stock Exchange.

Critics of private ownership of India's agricultural and industrial entities—most notably Mahatma Gandhi's independence movement—instead advocated for a self-sufficient, largely agrarian, communal village-based existence for India in the first half of the 20th century. Other contemporary criticisms of India's public sector targeted the lack of well-funded schools, public libraries, universities, hospitals and medical and engineering colleges; a lack seen as impeding an Indian replication of Britain's own industrialization in the previous century.

Post-Independence, the national consensus turned in favor of rapid industrialisation of the economy, a process seen as the key to economic development, improved living standards and economic sovereignty. Building upon the Bombay Plan, which noted the necessity of government intervention and regulation in the economy, the first Industrial Policy Resolution announced in 1948 laid down in broad strokes such a strategy of industrial development. Later, the Planning Commission was formed by a cabinet resolution in March 1950 and the Industrial (Development and Regulation) Act was enacted in 1951 with the objective of empowering the government to take necessary steps to regulate industry.

The first Prime Minister of India, Jawaharlal Nehru, promoted an economic policy based on import substitution industrialisation and advocated a mixed economy. He believed that the establishment of basic and heavy industry was fundamental to the development and modernisation of the Indian economy. India's second five year plan (1956–60) and the Industrial Policy Resolution of 1956 emphasized the development of public sector enterprises to meet Nehru's national industrialisation policy. His vision was carried forward by V. Krishnamurthy, a figure known as the "Father of Public sector undertakings in India". Indian statistician Prasanta Chandra Mahalanobis was instrumental to its formulation, which was later termed the Feldman–Mahalanobis model.