Segeberg is a Kreis (district) in the southern part of Schleswig-Holstein, Germany. Area 1334 km², population 248,500 (2000). The district's capital is Bad Segeberg.
The district of Segeberg consists of the agricultural plains between the cities of Neumünster and Hamburg. A southwestern portion of the hilly lakeland called "Holsteinische Schweiz" (Holsatian Switzerland) belongs to the district, as well as some northern suburbs of Hamburg.
Towns in Segeberg: Bad Segeberg, Wahlstedt, Bad Bramstedt, Kaltenkirchen, Norderstedt.