Between 1896 and 1898 he worked for the Benz company in Mannheim, then he continued in his studues and attended a technical school in Hildburghausen, Thuringia.

In December 1907 Hieronimus started to work as a constructor and test driver in Laurin & Klement motorbikes and car factory in Mladá Boleslav, Bohemia,[4] the predecessor of today's Škoda Auto.

In 1908, Hieronimus set a new speed record on the world's first permanent circuit at Brooklands, United Kingdom in Laurin & Klement FCS - 118.72 km/h on the 2.76-mile track.

[5] In Laurin & Klement FCR engine he succeeded to set a track record in the Zbraslav–Jíloviště hillclimb race (near Prague) in 1911 (3:44.2 min).

Otto Hieronimus was seriously injured in a car crash on 8 May 1922 during the Rieß uphill race and died later that day in Steyr city hospital aged 42.