The municipality of Alsbach-Hähnlein is a result of the amalgamation, which took place in 1977, of the formerly independent communities Alsbach and Hähnlein.
The earliest mention of Alsbach dates back to the year 773. It was recorded in the so-called "Lorscher Codex", the record book of Lorsch Monastery. In 1333, Hähnlein had its first documentary mention. Alsbach's landmark, the Alsbacher Schloss - Alsbach Castle was built around 1240.