The monarchy of Liechtenstein is the constitutional form of government by which a hereditary sovereign reigns as the head of state of Liechtenstein. The current monarch is Prince Hans-Adam II. The House of Liechtenstein, after which the sovereign principality was named in 1719, hails from Liechtenstein Castle in Lower Austria, which the family possessed from the middle of the twelfth century to the thirteenth century, and from 1807 onward. It is the only remaining European monarchy that practises strict agnatic primogeniture.

Constitutional monarchy, also known as limited monarchy, parliamentary monarchy or democratic monarchy, is a form of monarchy in which the monarch exercises their authority in accordance with a constitution and is not alone in making decisions. Constitutional monarchies differ from absolute monarchies in that they are bound to exercise powers and authorities within limits prescribed by an established legal framework.