Emperor Louis the Pious donated in 815 Untermühlheim together with Obermühlheim (today called Seligenstadt), which were then in the Frankish Maingau to Einhard.
In 1435, Mühlheim, as was so with many places in the area, was sold along with the Amt of Steinheim by the Lords of Eppstein to the Electorate of Mainz.