Hasselberg (Danish: Hasselbjerg) is a municipality in the district of Schleswig-Flensburg, in Schleswig-Holstein, Germany.

Besides the town of Hasselbjerg, the municipality also includes settlements Baggeland (also Bagland, Bag Lunden in German Baggelan ), Bobæk ( Bobeck ), Drejet ( Drecht ), Eckenhöh (Egehøj, formerly Lille Kidholm), Egebjerg ( Eckberg ), Engbjerg ( Engberg ), Eversholt ( Ewersholz ), Gejlbjerg ( Geilberg ), Gundelsby , Haberholt ( Hafferholz ), Gl.

Hasselbjerg ( Alt Hasselberg ), Holm, Hyholt ( Hüholz ), Kidholm (in Danish also Kiholm, Kieholm ), Kirsebærhøj ( Kisperhy ), Knorløk or Knorlykke( Knorrlück ), Markskel ( Marschall ), Møllemark ( Mühlenfeld ), Nelslyk ( Neelslück ), Nørremark ( Norderfeld ), Pugholt ( Pugholz ), Raaland ( Radeland ), Svendsholt( Schwensholz ), Svakketorp ( Schwackendorf ), Skjelrød ( Schellrott ), Skilleled( Scheideheck ), Strengtoft, Søndermark ( Süderfeld ), Vormshoved ( Wormshöft ) and Ulvsholt ( Wulfsholz ).

North of the village on the border with Kronsgaard municipality is the 19 ha protected Færgeskov (also Færensholt, ty.

In 1535, Haselbjerg is mentioned as a village with 6 farms belonging to Bukhavn estate.