In 1700, Antoniotto's father died, and, as the family fiefs went to his elder brother Alessandro, he chose a military career.

He succeeded the sick Josef Wenzel, Prince of Liechtenstein as Austrian Supreme Commander in Italy, and fought the retreating Franco-Spanish troops in the Battle of Rottofredo.

He taxed Genoa so hard (Ai Genovesi non lascerò altro che gli occhi per piangere; I will leave the Genoese only their eyes to weep), that he was chased on 5 December by a popular revolt led by Balilla.

In 1749, a year after the Treaty of Aix-la-Chapelle, he became plenipotentiary of the Austrian Netherlands under Prince Charles Alexander of Lorraine.

Count Johann Karl Philipp von Cobenzl became his successor as minister plenipotentiary in Brussels.