On-surface fabrication of covalently interlinked conjugated nanostructures has attracted significant attention, mainly because of the high stability and efficient electron transport ability of these structures. Here, from the interplay of scanning tunneling microscopy imaging and density functional theory calculations, we report for the first time on-surface formation of one-dimensional polyphenylene chains through Bergman cyclization followed by radical polymerization on Cu(110). The formed surface nanostructures were further corroborated by the results for the ex situ-synthesized molecular product after Bergman cyclization. These findings are of particular interest and importance for the construction of molecular electronic nanodevices on surfaces.