In this study, a cobalt-based/graphene oxide (GO) composite coating has been fabricated on the surface of the TC4 substrate/titanium alloy via laser cladding. The scanning speed of V₁=6 mm/s, feeding rate of V₂=1.2 r/min, and spot diameter of D=4 mm remain constant, and four different laser power settings of P₁ =1000 W, P₂=1300 W, P₃=1600 W, and P₄=1900 W are selected to investigate the effect of laser power on the microstructure and mechanical properties of the cobalt-based/GO composite coating. The results prove that the cladding layer mainly comprises the TiC, Co₂Ti, γ-Co, α-Ti, and Cr₃C₂ phases. GO reacted with the TC4 matrix under the reaction of low power to in situ composites TiC. Furthermore, it interacts with the semi-solid Co₂Ti structure and decomposes rapidly under a high-power reaction, mainly generating the Co₂Ti structure. When the laser power is P₂=1300 W, the cladding effect is optimal and the forming structure is uniform; subsequently, the cladding cobalt-based/GO coating is metallurgically bonded to the TC4 substrate. The microhardness of the cladding layer is 1100 HV0.2, which is 2.82 times that of the matrix having a microhardness of 390 HV0.2.