Revetment piles serve as critical infrastructure for protecting riverbanks and coastal regions from wave and current erosion. Their bending capacity is fundamental to ensuring structural safety and long-term durability. After addressing a newly developed polygonal prestressed concrete revetment pile, this study proposes an analytical calculation method for the flexural capacity of irregular cross-sections, implemented through an automated Python-based computational framework. A series of full-scale four-point bending tests were conducted to evaluate the influence of varying cross-sectional geometries, reinforcement configurations, pile lengths, and concrete grades. By integrating Digital Image Correlation (DIC) and photogrammetry, non-contact measurements of deformation, strain fields, and crack propagation were obtained to elucidate the flexural behavior and failure mechanisms. The results demonstrate that the proposed piles exhibit superior flexural capacity and ductility. The error between the calculated and experimental values ranges from -0.18 to 0.27, validating the precision of the proposed analytical model. The flexural process transitions through three distinct stages: the elastic stage, the cracked-working stage, and the plastic stage. Increasing the diameter of prestressed tendons simultaneously improves the cracking moment, yield moment, and ductility. While an increase in section width significantly enhances the cracking and yield moments, it leads to a reduction in deformation capacity. Furthermore, higher concrete strength delays crack initiation and elevates the overall flexural capacity, whereas the span effect associated with increased pile length results in a convergence of capacity differences but a significant amplification of deflection. These findings provide a robust theoretical and experimental foundation for the design and analysis of novel revetment piles.