The Boston Port Act is an Act of the Parliament of Great Britain (citation 14 Geo. III. c. 19) which became law on March 30, 1774, and is one of the measures (variously called the Intolerable Acts, the Punitive Acts or the Coercive Acts) that were designed to secure Great Britain's jurisdictions over her American dominions.

A response to the Boston Tea Party, it outlawed the use of the Port of Boston (by setting up a barricade/blockade) for "landing and discharging, loading or shipping, of goods, wares, and merchandise" until such time as restitution was made to the King's treasury (for customs duty lost) and to the East India Company for damages suffered. In other words, it closed Boston Port to all ships, no matter what business the ship had. Colonists objected that the Port Act punished all of Boston rather than just the individuals who had destroyed the tea, and that they were being punished without having been given an opportunity to testify in their own defence.

As the Port of Boston was a major source of supplies for the citizens of Massachusetts, sympathetic colonies as far away as South Carolina sent relief supplies to the settlers of Massachusetts Bay. This was the first step in the unification of the thirteen colonies. The First Continental Congress was convened in Philadelphia on September 5, 1774, to coordinate a colonial response to the Port Act and the other Coercive Acts.