This study presents the successful bottom-up synthesis of zigzag graphene nanoribbons (ZGNRs) with atomically precise zigzag edges. The method involves surface-assisted coligation and cyclodehydrogenation of specifically designed precursor monomers, which yield ZGNRs with well-defined edge structures. Using scanning tunneling spectroscopy, the researchers confirm the existence of edge-localized states with large energy splittings. The synthesis enables the characterization of predicted spin-related properties, such as spin confinement and filtering, and opens the possibility of incorporating the spin degree of freedom into graphene-based circuitry. ZGNRs with atomically precise edges are essential for exploring the fundamental electronic and magnetic properties of zigzag edges and for the controlled manipulation of their spin states. The study demonstrates that bottom-up approaches can achieve atomic precision in the synthesis of ZGNRs, unlike top-down methods, which often result in poorly defined edges. The unique U-shaped monomer used in this study allows for the formation of snake-like polymers and subsequent cyclization to produce ZGNRs with precise zigzag edges. The synthesis process involves two steps: first, the polymerization of monomers at 475 K, and second, cyclodehydrogenation at 625 K to form the final ZGNRs. The study also addresses the challenges of fabricating ZGNRs, including the strong electronic coupling between the ribbons and the metal surface, which can obscure the detection of electronic edge states. The researchers overcome this by transferring the ZGNRs onto insulating NaCl islands, where they are electronically decoupled from the metal substrate. This allows for the clear observation of edge states, as evidenced by differential conductance (dI/dV) maps showing three resonance peaks near the Fermi level with distinct energy splittings. The successful synthesis of ZGNRs with precise edges opens new opportunities for studying their electronic, magnetic, and spin properties, as well as for the development of ZGNR-based devices such as spin valves. The study highlights the importance of chemical design and in-situ STM monitoring in achieving precise surface reactions, and it represents a milestone in surface chemistry. The results demonstrate the potential of bottom-up synthesis for the controlled fabrication of graphene nanostructures with tailored properties.This study presents the successful bottom-up synthesis of zigzag graphene nanoribbons (ZGNRs) with atomically precise zigzag edges. The method involves surface-assisted coligation and cyclodehydrogenation of specifically designed precursor monomers, which yield ZGNRs with well-defined edge structures. Using scanning tunneling spectroscopy, the researchers confirm the existence of edge-localized states with large energy splittings. The synthesis enables the characterization of predicted spin-related properties, such as spin confinement and filtering, and opens the possibility of incorporating the spin degree of freedom into graphene-based circuitry. ZGNRs with atomically precise edges are essential for exploring the fundamental electronic and magnetic properties of zigzag edges and for the controlled manipulation of their spin states. The study demonstrates that bottom-up approaches can achieve atomic precision in the synthesis of ZGNRs, unlike top-down methods, which often result in poorly defined edges. The unique U-shaped monomer used in this study allows for the formation of snake-like polymers and subsequent cyclization to produce ZGNRs with precise zigzag edges. The synthesis process involves two steps: first, the polymerization of monomers at 475 K, and second, cyclodehydrogenation at 625 K to form the final ZGNRs. The study also addresses the challenges of fabricating ZGNRs, including the strong electronic coupling between the ribbons and the metal surface, which can obscure the detection of electronic edge states. The researchers overcome this by transferring the ZGNRs onto insulating NaCl islands, where they are electronically decoupled from the metal substrate. This allows for the clear observation of edge states, as evidenced by differential conductance (dI/dV) maps showing three resonance peaks near the Fermi level with distinct energy splittings. The successful synthesis of ZGNRs with precise edges opens new opportunities for studying their electronic, magnetic, and spin properties, as well as for the development of ZGNR-based devices such as spin valves. The study highlights the importance of chemical design and in-situ STM monitoring in achieving precise surface reactions, and it represents a milestone in surface chemistry. The results demonstrate the potential of bottom-up synthesis for the controlled fabrication of graphene nanostructures with tailored properties.