[1] Johann chose a military career and at age 21 entered the army as a lieutenant in a cuirassier regiment.

[1] During the Austro-Turkish War (1788–1791) he earned, in rapid succession, promotion to Major, Oberstleutnant, and Oberst (colonel).

He earned renown as a good cavalry officer and was honored with the Knight's Cross of the Military Order of Maria Theresa in 1790.

During the French Revolutionary Wars, he participated in an "outstandingly effective cavalry action" at Avesnes-le-Sec on 12 September 1793, where 4,663 Republican troops suffered losses of 2,000 killed and wounded with the Allies losing only 69 men.

He commanded a mixed cavalry-infantry brigade in Anton Sztaray's division at the Battle of Würzburg on 3 September 1796.

He took command of the main army after Archduke Charles resigned and held this responsibility until the end of the year.

As Prince of Liechtenstein, Johann made forward-thinking reforms, but also had an absolutist governing style.

He expanded agriculture and forestry and radically reorganized his administration, in an attempt to take the requirements of what was then a modern estate into account.