This study presents a novel application of the fuzzy Adomian decomposition method (FADM) to address the fuzzy Duffing differential equation, a significant non-linear problem frequently encountered in mechanical systems. The traditional methods of solving such equations often struggle to accommodate the inherent uncertainties present within the system parameters. By leveraging fuzzy logic, the FADM enables a more accurate representation of these uncertainties, resulting in robust approximate solutions. The method is systematically outlined, highlighting its effectiveness in producing convergent series solutions. Numerical examples are provided to illustrate the method’s application and efficacy in approximating solutions under varying fuzzy conditions. Results indicate that the fuzzy approach significantly improves solution accuracy and stability compared to traditional deterministic methods, making it a valuable tool in nonlinear dynamics.