Postural stability is influenced by several anthropometric factors as well as age. The aim of this study was to investigate the relationship between body height, body mass, BMI, and arch index with stabilometric parameters in physically active young adults. A total of 169 sport science university students participated in the study. Their arch index and their stabilometric parameters were measured using the P-Walk BTS platform. Spearman’s rank correlations showed a significant positive correlation between body mass and arch index (r = 0.25, p = 0.001), and BMI and arch index (r = 0.30, p < 0.001). Also, negative correlations were observed between body height and CoP speed (r = −0.22, p = 0.004) and CoP distance (r = −0.23, p = 0.003), as well as body weight and CoP speed (r = −0.17, p = 0.028) and CoP distance (r = −0.19, p = 0.015). Age was negatively correlated to postural sway variables (i.e., CoP distance, CoP area, and CoP speed). The findings suggest that, in physically active people, larger anthropometric values may confer stabilizing advantages, potentially due to increased body volume. Also, the significant correlation of age to stability metrics may highlight enhanced proprioceptive integration or adaptive neural mechanisms. The results highlight the importance of individualised proprioceptive training programmes, particularly for athletes of lower body mass or stature. Future research should extend on the results’ potential training and rehabilitative implications.