Company rule in India refers to the rule of the British East India Company on the Indian subcontinent. This is variously taken to have commenced in 1757, after the Battle of Plassey, when the Nawab of Bengal surrendered his dominions to the Company; in 1765, when the Company was granted the diwani, or the right to collect revenue, in Bengal and Bihar; or in 1773, when the Company established a capital in Calcutta, appointed its first Governor-General, Warren Hastings, and became directly involved in governance. The rule lasted until 1858, when, after the Indian Rebellion of 1857 and consequent of the Government of India Act 1858, the British government assumed the task of directly administering India in the new British Raj.

The expansion of the company's power chiefly took two forms. The first of these was the outright annexation of Indian states and subsequent direct governance of the underlying regions that collectively came to comprise British India. The annexed regions included the North-Western Provinces (comprising Rohilkhand, Gorakhpur, and the Doab) (1801), Delhi (1803), Assam (Ahom Kingdom 1828) and Sindh (1843). Punjab, North-West Frontier Province, and Kashmir were annexed after the Anglo-Sikh Wars in 1849–56 (Period of tenure of Marquess of Dalhousie Governor General). However, Kashmir was immediately sold under the Treaty of Amritsar (1850) to the Dogra Dynasty of Jammu and thereby became a princely state. In 1854, Berar was annexed along with the state of Oudh two years later.

The second form of asserting power involved treaties in which Indian rulers acknowledged the company's hegemony in return for limited internal autonomy. Since the company operated under financial constraints, it had to set up political underpinnings for its rule. The most important such support came from the subsidiary alliances with Indian princes during the first 75 years of Company rule. In the early 19th century, the territories of these princes accounted for two-thirds of India. When an Indian ruler who was able to secure his territory wanted to enter such an alliance, the company welcomed it as an economical method of indirect rule that did not involve the economic costs of direct administration or the political costs of gaining the support of alien subjects.