The Piracy Act 1721 (c.24) was an Act of the Parliament of Great Britain.

The long title and preamble of the Act were:

An Act for the more effectual suppressing of Piracy. Whereas the number of persons committing piracies, felonies, and robberies upon the seas is of late very much increased, and notwithstanding the laws already made and now in being, many idle and profligate persons have turned pirates, and betaken themselves to that wicked course of life, whereby the trade and navigation into remote parts will greatly suffer unless some further provision be speedily made for bringing such persons and all others who shall be any ways aiding and assisting, or in confederacy with them, to condign punishment:

Parts of the Act were superseded by the Piracy Act 1837.

All remaining parts of the Act were repealed on 5 November 1993 by the Statute Law (Repeals) Act 1993.

• 1717–1718 Acts of Grace