Accurate calculation of the compressive stiffness of micropiles (\(\:K_{s}\left(C\right)\)) is essential for forecasting load–displacement behavior and maintaining foundation serviceability in geotechnical structures. Conventional analytical and numerical methods frequently oversimplify soil-structure interaction and require substantial calibration, thereby limiting their applicability across diverse ground conditions. This paper presents a data-driven predictive approach that combines supervised machine learning techniques with a field-based micropile (\(\:MP\)) test database to address these limitations. A comprehensive dataset of 393 in-situ MP compression experiments was compiled after statistical preprocessing, including normalization, randomization, and outlier elimination based on the interquartile range criterion. Nine geotechnical and geometric characteristics were utilized as predictors of \(\:K_{s}\left(C\right)\). Five ensemble learning models—Gradient Boosting (\(\:GB\)), Light Gradient Boosting (\(\:LGB\)), Histogram-based Gradient Boosting (\(\:HGB\)), Extreme Gradient Boosting (\(\:XGB\)), and Categorical Boosting (\(\:CB\))—were created and refined with the Parrot Optimization Algorithm (\(\:POA\)) for hyperparameter optimization. The \(\:XG{B}_{POA}\) algorithm demonstrated the greatest prediction reliability. Comparative analyses demonstrated that \(\:XG{B}_{POA}\) decreased prediction error by 10–22% compared to other boosting models while ensuring enhanced convergence stability. The proposed \(\:POA\)-optimized boosting framework offers a precise, interpretable, and computationally efficient method for calculating \(\:K_{s}\left(C\right)\) directly from field data. This hybrid modeling methodology reconciles empirical testing with predictive analytics, providing a pragmatic solution for performance-oriented \(\:MP\) design and foundation system optimization in geotechnical engineering.