This paper presents the verification and applications of a numerical model developed for biaxially loaded high strength thin-walled rectangular concrete-filled steel tubular (CFST) slender beamcolumns with local buckling effects. The accuracy of the numerical model is established by comparisons of numerical results with existing experimental data. The verified numerical model is employed to investigate the effects of four parameters including concrete compressive strength, loading eccentricity, depth-to-thickness ratio and columns slenderness on the strength reduction factor and steel contribution ratio of CFST slender beam-columns under biaxial bending. The results obtained indicate that increasing each of the four parameters decreases the strength reduction factor. The steel contribution ratio is found to decrease with an increase in the concrete compressive strength and depth-to-thickness ratio but increase with increasing the loading eccentricity and column slenderness ratios. It is shown that the numerical model is efficient and accurate for predicting the load-deflection curves and strength envelopes for thin-walled rectangular CFST slender beamcolumns under biaxial loads. Benchmark numerical results given in this paper provide a better understanding of the local and global interaction buckling behavior of high strength thin-walled rectangular CFST slender beam-columns and are useful for the development of composite design codes.