The village is mentioned for the first time under the name »Diseldashausen« in a certificate of the monastery Corvey around the year 850.
The nobility von Grube who built the castle Grubenhagen on a ridge between Dassensen and Rotenkirchen probably owned a bailey in Dassensen. Until the first years of our century a house was standing next to today's school building, which was named the Klus. It was used by the castle owners and palace Rotenkirchen as accommodation at churchgoing.
The Dassensen church was finished in the year 1800 and contains a Baroque altar with a valuable crucifix.
There are the clubs of the TSV Dassensen and the sports shooter. Carnival is being celebrated at times.