The Khmelnytsky Uprising (also Khmel'nyts'kyi/Chmielnicki Uprising or Khmelnytsky/Chmielnicki Rebellion) refers to a rebellion or war of liberation in the lands of present-day Ukraine which raged from 1648-1654.

Under the command of Hetman Bohdan Khmelnytsky, Zaporozhian Cossacks allied with Crimean Tatars, along with the local Ukraine peasantry, fight several battles against the armies and szlachtian disorganized militia of the Polish-Lithuanian Commonwealth, and eradicate the control of the Polish szlachta, Roman Catholic priests and their Jewish intermediaries (arendators) in the area.The Uprising succeeds in ending the Commonwealth influence over Cossack lands, but effectively transfers those territories from the Polish to the Russian sphere of influence.

Further weakened by internal conflicts and hostilities with Sweden and Russian Tsardom, the power of the Commonwealth is severely diminished during this period (referred to in Polish history as The Deluge).