Introduction: Kathak is a very complex dance form in which greater emphasis is laid on foot work thus putting substantial amount of stress over the feet, which further leads to reduced medial longitudinal arch of feet. In previous studies regarding flexible pes planus, intrinsic muscle strengthening have been regarded as intervention and least focus is on extrinsic muscle strengthening. Aim: This study aimed to investigate the effect of tibialis posterior muscle (extrinsic muscle of foot) strengthening on flexible flat feet among the female Kathak dancers. Method: Screening of 75 Kathak dancers was done for the study on the basis of inclusion and exclusion criteria. And Hubscher’s maneuver was used as diagnostic criteria for flexible pes planus. Participants were assessed for flexible flat feet via navicular drop test. Each participant received 6weeks tibialis posterior strengthening protocol with 5 sessions per week. Among 75 participants 4 participants left the study. Result: Tibialis posterior strengthening had significantly improved the medial longitudinal arch in female kathak dancers by difference of 3.504 to 4.13mm for left foot and 4.018 to 4.658 mm for right foot. Conclusion: The result of this study provide evidence to suggest that tibialis posterior muscle strengthening may improve the medial longidunial arch in female kathak dancers.