AbstractThe bond strength, resistivity and corrosion resistance of Q235 steel coated with composites containing various concentrations of carbon nanotubes, graphene and waterborne polyurethane (CNTs/Gr/WPU) were evaluated in a 5% NaCl solution. Additionally, the galvanic corrosion between the coated steel and galvanised steel was investigated through galvanic potential, galvanic current, corrosion morphology and corrosion rate. The results show that the CNTs/Gr/WPU‐coated steel exhibits excellent adhesion and conductivity. Moreover, the incorporation of CNTs and Gr can effectively enhance the corrosion resistance of the CNTs/Gr/WPU‐coated steels in the 5% NaCl solution. The trends of the galvanic potentials and galvanic current densities of CNTs/Gr/WPU‐coated steel with different mass fractions coupled with galvanised steel are similar. The CNTs/Gr/WPU‐coated steels exhibit severe galvanic corrosion when coupled with galvanised steel.