The operating ambient of flexible electronics interconnects is a complex environment that includes mechanical deformation, electric current, and temperature. It is a potential threat to the long‐term service reliability of flexible electronic devices. This paper aims to develop a multiphysics fatigue model for flexible metal films. The effect of multiphysics fields is considered in the Coffin–Manson relationship based on reasonable simplification. The fatigue behavior of copper films of various thicknesses on a flexible substrate was investigated when electrical current and mechanical displacement loads were applied simultaneously. The developed model is validated to compare with experimental results. The numerical results show that it can analyze the effect of multiphysics fields and predict the fatigue life of copper films. Therefore, it could be a means to assess the fatigue performance of metal films on flexible substrates in multiphysics fields.