Diekholzen is a village and a municipality in the district of Hildesheim, in Lower Saxony, Germany. It is situated approximately 7 km southwest of Hildesheim on the Beuster, a tributary of the Innerste.

In 1974, the former villages of Diekholzen, Söhre, Barienrode and Egenstedt were united to form the municipality of Diekholzen. Each village has its own history and various sights. Most of the inhabitants are Roman Catholics. The largest village of the municipality is Diekholzen with an administration building, a school, a hospital, several shops, a supermarket, some restaurants and a hotel. Several times a day, each village of the municipality is accessible from Hildesheim and from Alfeld by bus.