The Landtag of Hesse is the unicameral parliament of the State of Hesse in the Federal Republic of Germany. It convenes in the Stadtschloss in Wiesbaden. As a legislature it is responsible for passing laws at the state level and enacting the budget. Its most important function is to elect and control the state government. The constitution of the State of Hesse describes the role of the Landtag in sections 75 to 99.

A Landtag is generally the legislative assembly or parliament of a federated state or other subnational self-governing entity in German-speaking nations. It is usually a unicameral assembly exercising legislative competence in non-federal matters.