Neighbouring districts are Kassel, Werra-Meißner, Hersfeld-Rotenburg, Vogelsberg, Marburg-Biedenkopf, and Waldeck-Frankenberg.

After they merge close to Felsberg, the Eder enters the Fulda to the north at Edermunde.

The southeast of the district includes a portion of the Knüllgebirge range of low mountains; the highest elevation is 634 metres (2,080 ft).

In the east, the geology of the Knüllgebirge is dominated by the clastic Triassic strata of the Middle Buntsandstein, as is the western region around the Gilserberg.

In the district of Fritzlar there are outcrops of younger Upper Buntsandstein, known as the Röt Formation, because of its red colour.