Lubomirski's Rokosz, or Lubomirski's Rebellion (Polish: rokosz Lubomirskiego), was a rebellion against Polish King Jan II Kazimierz Vasa, initiated by the Polish nobleman, Jerzy Sebastian Lubomirski.
In 1665-66, Lubomirski's supporters paralyzed the proceedings of the Sejm. Lubomirski himself, with the support of part of the state army and of levee-en-masse (pospolite ruszenie) forces, defeated the King's army at Częstochowa (1665) and royal forces, led by the future King Jan III Sobieski, at Mątwy (1666).
The rebellion ended with the Agreement of Łęgonice, which forced the King to give up his planned reforms and the introduction of vivente-rege royal elections. Lubomirski himself, now a broken man, died soon after.