It is a part of the municipality of Dinkelland, and lies about 10 km north of Oldenzaal.

[1] The statistical area "Ootmarsum", which also can include the peripheral parts of the town, as well as the surrounding countryside, has a population of around 3650.

In November 917, Radboud, bishop of Utrecht, died in Ootmarsum.

[3] In the 16th century Ootmarsum was occupied by the Spanish during the Eighty Years War but in 1597 was captured by Maurice, Prince of Orange.

Ootmarsum was a separate municipality until 2001, when it became a part of Dinkelland,[4] together with Denekamp and Weerselo.