<jats:title>Abstract</jats:title><jats:sec> <jats:title>Background</jats:title> <jats:p>Accumulating evidence indicates that abnormal foot posture are risk factors for knee osteoarthritis (OA). However, the relationship between foot posture and tibiofemoral contact force (CF) during habitual weight-bearing activities remains unclear. This study aimed to determine the association between tibiofemoral CF and foot posture while walking.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>In total, 18 patients with knee OA and 18 healthy individuals participated in this cross-sectional study. Foot parameters were evaluated by Foot Posture Index (FPI), Staheli Arch Index (SAI), hallux valgus angle, calcaneus inverted angle relative to the floor as a static rearfoot posture, navicular height, and toe grip strength. In addition, all participants underwent kinetic and kinematic measurements during a self-selected speed gait. The measurement device used was the three-dimensional motion analysis system with a sampling rate of 120 Hz. The musculoskeletal model, which has 92 Hill-type muscle–tendon units with 23 degrees of freedom, was used to calculate tibiofemoral CF. Partial correlations was used to investigate the association between foot parameters and total, medial, and lateral tibiofemoral CF of the first and second peaks while controlling for gait speed.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>A significant negative correlation was observed between Walking SAI and first peak medial tibiofemoral CF in control participants (<jats:italic>r</jats:italic> = -0.505, <jats:italic>p</jats:italic> = 0.039). SAI was also significantly positively correlated with first peak medial tibiofemoral CF in patients with knee OA (<jats:italic>r</jats:italic> = 0.482, <jats:italic>p</jats:italic> = 0.042).</jats:p> </jats:sec><jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Our findings revealed a correlation between the medial first peak tibiofemoral CF and the SAI. This study indicates that people with knee OA and flatfoot have excessive first medial tibiofemoral CF during walking.</jats:p> </jats:sec>