In this paper, the aim is to present a method for accurately estimating the fatigue life of rubber engine mounts used in internal combustion engines based on fatigue damage evaluation parameters. In the first step, to determine the mechanical properties and establish the constitutive equation of the rubber used in the engine mount, uniaxial tension, uniaxial compression, and planar tension tests were performed, and the Mooney–Rivlin model was employed to describe the hyperelastic behavior of the material. Subsequently, fatigue life tests were conducted on 3D dumbbell specimens and engine mounts under specified laboratory conditions, in order to obtain experimental fatigue life data. Next, fatigue damage evaluation parameters—including strain energy density, effective stress, principal Green–Lagrange strain, Almansi–Euler strain, and octahedral shear strain—were computed using the finite element method under loading conditions identical to those of the fatigue life tests for both the 3D dumbbell specimen and the engine mount. Then, fatigue life estimation models were developed by fitting a power-law relationship between the calculated damage parameters and the experimental fatigue life of the 3D dumbbell specimen. Finally, by substituting the computed fatigue damage parameters of the engine mount into the corresponding models, the estimated fatigue lives of the engine mount were obtained and compared with experimental results. Calculation of the correlation coefficient for each model revealed that the model based on the octahedral shear strain and principal Green–Lagrange strain provides the highest accuracy in predicting the fatigue life of the engine mount.