Kmety's father was a noble but poor evangelist vicar who died in 1818, so his brother Pál (Paul) brought him up.

Kmety was leading four companies when he went with Lajos Kossuth to János Móga's camp, and with them fought the Battle of Schwechat.

Kmety didn't fight in the Battle of Kápolna because of Henryk Dembiński's poor leadership, although he covered the retreating Hungarian army.

On 13 June Kmety defeated the Austrian troops led by Franz Wyss in the Battle of Csorna, and because of this he received the general title.

At the beginning of the Crimean War Kmety returned to the Ottoman Empire where he was defeated by the Russians at the Siege of Kars on 29 September 1855.

In recognition of his help, after Kmety's death the Turks erected a statue that still stands in Kensal Green Cemetery (London).