The mechanical behavior of nonwoven fabrics as reinforcement in cementitious composites remains insufficiently explored, particularly from a numerical modeling perspective, despite their growing interest as sustainable alternatives to conventional textiles. This study presents a simplified, engineering-oriented numerical modeling framework for reproducing the flexural mechanical response of cementitious composites reinforced with flax nonwoven fabric. Four-point bending (flexural) behavior of nonwoven fabric–reinforced cementitious composites was numerically simulated using ANSYS software. The model is developed using Finite Element Analysis (FEA) and incorporates a Representative Volume Element (RVE) approach to account for the heterogeneous fiber–matrix interaction. The required material properties were iteratively calibrated using existing experimental data for three composite configurations comprising 4, 5, and 6 layers. The proposed model demonstrated agreement with experimental results within the investigated configurations, achieving normalized root mean square errors (nRMSE) of 5.2%, 4.6%, and 2.07% for the respective configurations. Furthermore, correlations between material parameters and geometric factors were identified, providing preliminary insights for estimating model input properties from easily measurable variables. Finally, sensitivity analyses were performed to evaluate the influence of key geometric and material parameters on the structural response, offering valuable insights for the optimized design of nonwoven fabric-reinforced cementitious composites.