Ypsilantis played an important role in the Greek War of Independence, leading several key battles.

[1] In 1821 he took part in the Wallachian uprising under the leadership of his brother Alexandros, that indirectly benefited the Principalities of Moldavia and Wallachia.

[2] After the failure of the uprising in Wallachia, he went to the Morea (Peloponessus), where the Greek War of Independence had just broken out, as representative of Filiki Etaireia and his brother.

He was one of the most conspicuous of the Phanariote leaders during the early stages of the revolt, though he was much hampered by the local chiefs and by the civilian element headed by Alexandros Mavrokordatos;[1] as a result the organisation of a regular army was slowed and operations were limited.

[3] He took part in the sieges of Tripolitsa, Nafplion and the Battle of Dervenakia, securing the Greek dominion in Morea.