This article introduces a novel method for investigating crack propagation in porous quasi-brittle structures. The method combines isogeometric analysis (IGA) with higher-order phase-field theory. IGA is particularly useful for representing complex geometries through high-order Non-Uniform Rational B-Spline (NURBS)-based elements. It gives it an advantage over conventional methods that rely on enriched nodes. The phase-field approach uses a scalar field to implicitly define the trajectory of cracks, eliminating the need to predefine an initial crack location. The study was conducted on a porous plate model with multiple perforations. The porosity level significantly affects the structural integrity of the domain under consideration. The degradation functions that characterize material softening concerning porosity are obtained through careful examination. These degradation functions are further implemented into numerical problems to observe the effect of porosity on crack initiation and propagation behavior. The results have demonstrated the proposed approach’s efficiency and accuracy in analyzing porous concrete’s failure behavior. The analysis results contribute to advancing our understanding of crack propagation and showcase the efficacy of the presented methodological framework in enhancing predictive capabilities in structural mechanics.