<p>Weakly cemented soft rock exhibits strong water sensitivity and time-dependent deformation, which can threaten the long-term stability of foundations and underground structures. In this paper, triaxial creep tests were conducted on weakly cemented soft rock specimens with moisture contents of 0%, 5.6%, 10.8%, and 18.6% to investigate the influence of water content on creep behavior and long-term strength. The results show that increasing moisture content and deviatoric stress promote the transition from stable creep to unstable creep, with greater creep deformation and lower creep failure stress. An improved steady-state creep-rate inflection method was used to determine the long-term strength, and a quantitative relationship between moisture content and long-term strength was established. Scanning electron microscopy observations indicate that hydration loosens the microstructure, increases pore development, and reduces cohesion, thereby accelerating creep damage. Based on fractional calculus and damage mechanics, a moisture-dependent fractional-order creep damage model was developed by modifying the Burgers model to describe both decelerating and accelerated creep stages. The model parameters were optimized using a hybrid particle swarm optimization–Levenberg–Marquardt algorithm, and the model showed good agreement with the experimental results. The proposed model provides a useful approach for describing water-induced creep deformation and evaluating the long-term failure tendency of weakly cemented soft rock under different moisture conditions.</p>