Johann Nepomuk Karl, Prince of Liechtenstein (Full name: Johann Nepomuk Karl Borromäus Josef Franz de Paula) (6 July 1724 – 22 December 1748) was the Prince of Liechtenstein between 1732 and 1748. He was the son of Johann Josef Anton.
When his father died, Johann Nepomuk Karl was only eight and his uncle Josef Wenzel ruled as regent. Nepomuk Karl came of age in 1745 and thus took control of Liechtenstein's affairs. In 1744 he had married his cousin Maria Josepha, Countess of Harrach-Rohrau (20 November 1727 – 15 February 1788), daughter of Count Friedrich August von Harrach-Rohrau. The couple had two daughters; Marianne (1745–1752) and Maria Antonia (13 June 1749 – 28 May 1813).
Johann Nepomuk died in Wischau three years later at the age of 24 leaving no male descendants.