Cumulene compounds are notoriously difficult to prepare and study due to dramatically increasing reactivity with increasing number of consecutive double bonds. In this respect, the emerging field of on‐surface synthesis provides exceptional opportunities because it relies on reactions on clean metal substrates under well‐controlled ultrahigh vacuum conditions. Here we report the on‐surface synthesis of a polymer linked by cumulene‐like bonds on a Au(111) surface via sequential thermally activated dehalogenative C-C coupling of a tribenzo‐azulene precursor equipped with two dibromomethylenes. The structure and electronic properties of the resulting polymer with cumulene‐like pentagon‐pentagon and heptagon‐heptagon connections have been investigated by means of scanning probe microscopy and spectroscopy methods and X‐ray photoelectron spectroscopy, complemented by density functional theory calculations. Our results provide perspectives for the on‐surface synthesis of compounds containing cumulene‐like bonds, as well as protocols relevant to the stepwise fabrication of carbon‐carbon bonds on surfaces.