This study presents an effective numerical framework for hydrogen-assisted cracking employing the Scaled boundary finite element method (SBFEM) and an adaptive phase field model (PFM). For local adaptive refinement quadtree meshing technique is used which provides computationally faster solutions. The SBFEM, unlike conventional models like the finite element method and the boundary element method (BEM), or extended finite element method (XFEM), efficiently handles hanging nodes, making it suitable for polygonal structures. The phase field model is employed for damage prediction, capable of forecasting all stages of crack development, including initiation, propagation, and failure. A staggered solution approach is used to solve the coupled elasticity, phase field, and diffusion equations. The elasticity equation is two-way coupled with the phase field equation, as the phase field value influences material stiffness, and strain energy affects the phase field variable. The diffusion equation is one-way coupled to both elasticity and phase field equations, capturing the impact of hydraulic stress on hydrogen concentration and its subsequent effect on the critical energy release rate, altering the phase field value. A series of numerical examples are solved to validate the proposed framework, with results demonstrating close agreement with existing models across all scenarios, affirming the effectiveness of the proposed approach in predicting hydrogen-assisted cracking.