The one-state solution, sometimes also called a bi-national state, is a proposed approach to resolving the Israeli–Palestinian conflict, according to which one state must be established between the River Jordan and the Mediterranean. Proponents of this solution advocate a single state in Israel, the West Bank and the Gaza Strip. The term one-state reality describes the belief that the current situation in Israel/Palestine is de facto one-state.

Various models have been proposed for implementing the one-state solution. One such model is the unitary state, which would comprise a single government on the entire territory with citizenship and equal rights for all residents, regardless of their ethnicity or religion, similar to Mandatory Palestine. Some Israelis advocate a version of this model in which Israel will annex the West Bank but not the Gaza Strip and remain a Jewish and democratic state with a larger Arab minority. A second model calls for Israel to annex the West Bank and create an autonomous region for the Palestinians there. A third version would involve creating a federal state with a central government and federative districts, some of which would be Jewish and others Palestinian. A fourth model involves an Israeli-Palestinian confederation, a de facto two-state solution where both independent states share powers in some areas and Israelis and Palestinians have residency rights in each others' nations.

Though increasingly debated in academic circles, the one-state solution has remained outside the range of official efforts to resolve the conflict, where it is eclipsed by the two-state solution. According to a 2017 survey, support for a one-state solution stands at 36% among Palestinians, 19% among Israeli Jews and 56% among Israeli Arabs. However, interest in a one-state solution is growing as the two-state approach has not managed to reach a final agreement.