Solar-driven interfacial seawater evaporation is a pivotal technology for relieving global freshwater shortage. Although two-dimensional photothermal evaporators feature low cost and high flexibility, they are plagued by insufficient mechanical robustness, poor thermal localization and low stability, hindering practical applications. Herein, we use a continuous dynamic electrostatic cladding yarn strategy to build core–shell structured yarns, with a high-modulus stainless steel wire as the core and a transition metal-modified carbon-based photothermal polymer as the shell. The PM-1.35 yarn exhibits an ultrahigh tensile strength of 3692 MPa, a water evaporation rate of 2.18 kg·m^-2 h^-1 and an efficiency of 89.6% under 1 sun illumination. The integrated system delivers a maximum open-circuit voltage of 150.3 mV and stably generates 40.3 mV by waste heat recovery. This work integrates robust mechanical properties and outstanding photothermal activity, providing a new technical route for practical seawater desalination and thermoelectric cogeneration.