Obersinn lies in the Würzburg Region and is split into a Spessart half and a Rhön side by its namesake river, the Sinn.

The municipality has the following subdivisions (Gemarkungen, traditional rural cadastral areas): Obersinn, Burgjoß, Forst Aura.

The community’s arms might be described thus: A pale wavy argent, dexter gules in chief a scallop shell reversed of the first, in base dancetty of three of the first, sinister vert in chief a letter H, on whose cross stroke a figure of 4, in base a beech leaf in bend sinister of the first.

The three silver points in a red field, the so-called “Franconian rake”, recall the community’s long period of ownership by the Prince-Bishopric (Hochstift) of Würzburg.

It symbolized the four-lord condominium in this area, to which Obersinn belonged (H stands for Herr or Herrschaft, German for “Lord” or “Lordship”).