Ernst Ludwig was born in Berlin, the son of Ferdinand Dümmler, Sr. (1777-1846), a Berlin bookseller. He studied law, classical philology and history, among other things, at Bonn under Johann Wilhelm Löbell, and in Berlin, where his influences were Leopold von Ranke and Wilhelm Wattenbach. His doctorate dissertation, De Arnulfo Francorum rege (Berlin, 1852), was a notable essay among historians.
He entered the faculty at Halle in 1855, and started an historical seminar. In 1858 he became an associate professor, in 1866 full professor. In 1875, he became a member of the revised committee directing the Monumenta Germaniae Historica, himself undertaking the direction of the section "Antiquitates". In 1888 he became president of the central board in Berlin. This was an official recognition of Dümmler's leading position among German historians.
In addition to numerous critical works and editions of texts, he published:
His great work was the Geschichte des ostfränkischen Reiches (Berlin, 1862-1865, 2 volumes; 2nd ed. 1887-1888, in 3 volumes). In conjunction with Wattenbach he completed the Monumenta Alcuiniana (Berlin, 1873), which had been begun by Philipp Jaffé, and with Rudolf Köpke he wrote Kaiser Otto der Grosse (Leipzig, 1876).
He edited the anonymous Lorsch riddles twice--first in 1879 and then again two years later in 1881. He also edited the first and second volumes of the "Poetae latini aevi Carolini" for the Monumenta Germaniae historica (Berlin, 1881-84).