Frederick was born in Kassel. As the eighth child of Landgrave Maurice of Hesse-Kassel, he was awarded Hesse-Eschwege by a decree of his father, which was imposed on his father by his eldest brother William V shortly before Maurice had to abdicate to avoid an impending bankruptcy. At the instigation of his second wife, Juliane of Nassau-Siegen, Maurice set aside a quarter of his country, the so-called Rotenburg Quarter, to be divided among his married sons. Of those, Herman IV received the Rotenburg area, Frederick received Eschwege and Ernest received the former Lower County of Katzenelnbogen, around Rheinfels Castle.
