The Tea Act 1773 (13 Geo 3 c 44) was an Act of the Parliament of Great Britain. The principal objective was to reduce the massive amount of tea held by the financially troubled British East India Company in its London warehouses and to help the struggling company survive. A related objective was to undercut the price of illegal tea, smuggled into Britain's North American colonies. This was supposed to convince the colonists to purchase Company tea on which the Townshend duties were paid, thus implicitly agreeing to accept Parliament's right of taxation. Smuggled tea was a large issue for Britain and the East India company, since approximately 86% of all the tea in America at the time was smuggled Dutch tea.

The Act granted the Company the right to directly ship its tea to North America and the right to the duty-free export of tea from Britain, although the tax imposed by the Townshend Acts and collected in the colonies remained in force. It received the royal assent on May 10, 1773.

Colonists in the Thirteen Colonies recognized the implications of the Act's provisions, and a coalition of merchants, smugglers, and artisans similar to that which had opposed the Stamp Act 1765 mobilized opposition to delivery and distribution of the tea. The company's authorised consignees were harassed, and in many colonies successful efforts were made to prevent the tea from being landed. In Boston, this resistance culminated in the Boston Tea Party on December 16, 1773, when colonists (some disguised as Native Americans, since they identified themselves as Americans and no longer considered themselves British subjects) boarded tea ships anchored in the harbour and dumped their tea cargo overboard. Parliamentary reaction to this event included passage of the Coercive Acts, designed to punish Massachusetts for its resistance, and the appointment of General Thomas Gage as royal governor of Massachusetts. These actions further raised tensions that led to the eruption of the American War of Independence in April 1775.

Parliament passed the Taxation of Colonies Act 1778, which repealed a number of taxes (including the tea tax that underlay this act) as one of a number of conciliatory proposals presented to the Second Continental Congress by the Carlisle Peace Commission. The commission's proposals were rejected. The Act effectively became a "dead letter", but was not formally removed from the books until passage of the Statute Law Revision Act 1861.

The Parliament of Great Britain was formed in May 1707 following the ratification of the Acts of Union by both the Parliament of England and the Parliament of Scotland. The Acts ratified the treaty of Union which created a new unified Kingdom of Great Britain and created the parliament of Great Britain located in the former home of the English parliament in the Palace of Westminster, near the City of London. This lasted nearly a century, until the Acts of Union 1800 merged the separate British and Irish Parliaments into a single Parliament of the United Kingdom with effect from 1 January 1801.