Biodegradable polymers are a class of polymers designed to break down after having fulfilled their intended function. This unique property makes them very promising in healthcare applications such as sutures, stents, and scaffolds, as the need for retrieval surgery is completely eliminated. In this context, modelling of hydrolysis degradation in polymers is critically needed in view of accelerating device development. However, predicting device performance and service life under complex environments remains challenging, due to the presence of highly coupled phenomena [1]. This study tries to fill this gap by developing a general thermodynamically consistent constitutive framework for degrading polymers under loads that couples water and short soluble chains diffusion, hydrolysis reaction, and large, elasto-viscoplastic deformations, building on our previous work for hydrogels [2]. In particular, a novel constitutive model for hydrolytic chain scission has been developed considering the effects of autocatalysis and chain scission mechanism. The chain scission model is then used to predict the evolution of the polymer's mechanical properties during degradation. The model is implemented in a finite element framework for solving representative boundary-value problems. Comparisons between the model predictions and experimental data suggest that the developed model can predict the coupled phenomena and reveal the effects of design factors on the degradation process. The proposed constitutive framework could enable the rational design of biodegradable polymer materials and devices under realistic service conditions.