Warendorf (German pronunciation: [ˈvaːʁəndɔʁf]) is a Kreis (district) in the northern part of North Rhine-Westphalia, Germany.

Neighboring districts are Steinfurt, Osnabrück (district), Gütersloh, Soest, district-free city Hamm, Coesfeld and the district-free city Münster.

When it became part of the Prussian Province of Westphalia, the new government in 1816 created the districts of Warendorf and Beckum.

The Lippe River forms part of the southern border of the district.

The wavy line comes from the Beckum coat of arms, and symbolized the richness of water in the area, especially the Werse river.