The town was heavily damaged in the 1763 Komárom earthquake.
Komárom was formerly a separate village called Újszőny. In 1892 Komárom and Újszőny were connected with an iron bridge and in 1896 the two towns were united under the name city of Komárom.
In 1918 it was split by the newly created border of Czechoslovakia. In 1920 Hungary was forced to sign the Treaty of Trianon recognizing the new imposed borders including the border with Czecho-Slovakia. The loss of its territory created a sizable Hungarian minority in Slovakia. The Slovak part is today Komárno, Slovakia. In 1938 the entire city was returned to Hungary, its Regent, Admiral Horthy receiving a tumultuous welcome from the citizens as he crossed the old bridge and entered the formerly dismembered part. At the end of World War II the city was again divided between Hungary and Czecho-Slovakia.
Komárom and Komárno are connected by two bridges: The older iron bridge, and a newer lifting bridge. A third bridge is planned, with the vast majority of funding coming from the European Union's Connecting Europe Facility.
The two towns used to be a border crossing between Czecho-Slovakia (today Slovakia) and Hungary, until both countries became part of the Schengen Area, resulting in all immigration and customs checks being lifted on December 12, 2007.