Lubomirski's rebellion or Lubomirski's rokosz (Polish: rokosz Lubomirskiego), was a rebellion against Polish King John II Casimir that was initiated by Jerzy Sebastian Lubomirski, a member of the Polish nobility.
From 1665 to 1666, Lubomirski's supporters paralyzed the proceedings of the Sejm. Lubomirski, with the support of part of the army and the conscripted pospolite ruszenie, defeated royal forces at the Battle of Matwy in 1666. The rebellion ended with the Agreement of Łęgonice, which forced the King to give up his planned reforms like the introduction of vivente rege royal elections. Lubomirski, now a broken man, died soon afterward.