Wietmarschen is a unitary municipality located in the district of Grafschaft Bentheim within the state of Lower Saxony, Germany. The municipality is composed of several distinct villages, including Füchtenfeld, Schwartenpohl, Lohnerbruch, Nordlohne, and Lohne.
While Wietmarschen serves as the namesake for the municipality and is its second-largest village, Lohne is the largest settlement in the area. The town hall of the municipality is situated in Lohne.