Cölbe's municipal area lies on the southern edge of the Burgwald, a low mountain range and part of the Hessisches Bergland (Hessian Highland), and borders directly on the university city of Marburg to the south. The namesake constituent community is found on a bow in the river Lahn where it bends from its mainly easterly flow to a mainly southerly one.
Cölbe borders in the northwest on the town of Wetter, in the northeast on the town of Rauschenberg, in the east on the town of Kirchhain, in the south on the town of Marburg, and in the west on the community of Lahntal (all in Marburg-Biedenkopf).
Cölbe's civic coat of arms might be described thus: Gules a bend argent surmounted by six hearts reversed gules in bend three and three. Reversed hearts are also taken in heraldry as stylized testicles.