Diarylethene derivatives are photochromic molecular switches, undergoing a ring-opening/-closing reaction by illumination with light. The symmetry of the closed form is determined by the Woodward–Hoffmann rules according to which the reaction proceeds by conrotatory rotation in that case. Here, we show by a combined approach of scanning tunneling microscopy (STM) and density functional theory (DFT) calculations that the open isomer of 4,4′-(4,4′-(perfluorocyclopent-1-ene-1,2-diyl)bis(5-methylthiophene-4,2-diyl)dipyridine) (PDTE) retains its open form upon adsorption on a Ag(111) surface. It can be switched into a closed form, which we identify as the disrotatory cyclization product, by controlled manipulation with the STM tip. Evidence of an electric-field dependent switching process is interpreted on the basis of a simple electrostatic model, which suggests that the reaction proceeds via an “upright” intermediate state. This pathway thus strongly differs from the switching reaction in solution.