From 1790 to 1796 Mrongovius taught Polish and Greek at the Collegium Fridericianum. In 1796 he married Wilhelmina Luise Paarmann.
Mrongovius was an educator who taught Polish and Greek at the Collegium Fridericianum from 1790 to 1796, before marrying Wilhelmina Luise Paarmann in 1796.