Wietmarschen (Northern Low Saxon: Wietmöschken) is a unitary municipality (Einheitsgemeinde) in the district of Grafschaft Bentheim in Lower Saxony, Germany.

The community's highest elevation is the Rupingberg in Lohne at 50 metres (160 ft) above sea level.

The municipality is divided into six Ortsteile named Wietmarschen, Füchtenfeld, Schwartenpohl, Lohnerbruch, Nordlohne and Lohne.

The community of Wietmarschen diverges sharply from the rest of the district with regard to religion in that it has a largely Catholic character.

In February 2006, the community's religious affiliations broke down thus: Wietmarschen's council is made up of 28 councillors.