In 1821 districts were created in Hessen, including the districts Fritzlar, Homberg, Melsungen and Ziegenhain. In 1932 the districts Fritzlar and Homberg were merged; in 1974 the three districts Fritzlar-Homberg, Melsungen and Ziegenhain were merged into the Schwalm-Eder district.
The two rivers Schwalm and Eder gave the district its name. After they merge near Felsberg the Eder enters the Fulda at the north of district. In the southeast of the district are the hills of the Knüll, with the highest elevation being 634 m. North of it are the hills of the Homberger Hochland. The center of the district is largely rural, and is surrounded by the mountains of the Knüll, the Stölzinger Gebirge and the Kellerwald with the 675 meter-high Wüstegarten mountain.