The study investigates the bearing capacity of specially shaped, concrete-filled steel tube columns, emphasizing the impact of reentrant corners. A novel design was proposed, involving the welding of one cold-formed, thin-walled square steel tube and two U-shaped steel tubes into an L-shaped configuration, which is then filled with concrete to form an L-shaped concrete-filled cold-formed thin-walled steel tubular columns. To explore this concept, a series of axial load tests were conducted on 10 specimens with total of 5 groups. These experiments were complemented by finite element analysis to assess the effects of various parameters, including steel tube thickness, protrusion length of the U-shaped tubes, and steel material strength, on the structural integrity and ductility of the columns. Results indicate that the predominant failure mechanism involved localized buckling in the upper-middle region. An increase in the U-shaped tubes protrusion length was found to enhance structural capacity up to a certain threshold, beyond which flexural-torsional failure becomes prevalent. Additionally, both the structural capacity and ductility of the columns were positively correlated with increases in steel tube thickness and material strength. The strength of the concrete was observed to have a minimal impact on the initial stiffness and peak load of the columns, yet significantly influenced the descending phase of the load-deflection curve. Moreover, concrete stresses were more pronounced at the reentrant corners of the specimen ends and mid-sections compared to the lateral mid-sections, suggesting an enhanced restraint by the combination of U-shaped and rectangular steel tubes in these regions. According to the“unified theory”, two sets of calculation formulas for loadbearing capacity were proposed. These formulas not only align closely with experimental results but also demonstrate robust applicability across a wide range of constraint effect coefficients, from 0.44 to 1.94.