On-surface chemistry is promising way in order to achieve the bottom-up construction of covalently-bonded molecular precursors into extended atomically-precise polymers adsorbed on surfaces. These polymers exhibit unprecedented physical or chemical properties which are of great interest for various potential applications. The fabrication of these nanostructures was mainly obtained in ultrahigh vacuum (UHV) environment on single-crystal surfaces, i. e. noble metal surfaces, by thermal annealing as stimulus to provoke the polymerisation with a "catalytic" role of the surfaces adatoms. Nevertheless, photons are also a powerful source of energy to induce the formation of covalent architectures, even if it is less-used on surfaces than in solution. In this minireview, we discuss the photoinduced on-surface polymerization from the basic mechanisms of photochemistry to the formation of extended polymers on different kinds of surfaces which are characterized by scanning probe microscopies.