<p>This study presents a comprehensive transient modeling framework to characterize the stress-diffusion behavior of fiber-reinforced hydrogel composites. The proposed model introduces an intermediate configuration to effectively decouple swelling and elastic deformation, while employing Fick’s diffusion law to describe solvent transport within the hydrogel matrix. Unlike previous models, our model accounts for both highly nonlinear behavior and dispersibility of the fibers. We have developed a finite element implementation that incorporates diffusion effects, which has been successfully integrated into Abaqus through a user element subroutine. Numerical results demonstrate excellent agreement with both theoretical predictions and existing numerical solutions. Within this computational framework, we systematically investigate the stress-diffusion coupling in entanglement chain hydrogels and fiber-reinforced hydrogel composites. The parametric studies provide valuable insights into how key factors, including entanglement chain ratio, fiber content, stiffness, and distribution, govern the mechanical and mass transport properties of these materials. These findings elucidate the fundamental mechanisms behind the anisotropic mechanical and diffusion behavior observed in hydrogel systems and their composite variants.</p>