The study evaluated the associations between postural asymmetry and refractive errors in 567 Chinese students aged 12–18 years (mean age 14.96 ± 1.60 years, 43.4% boys). The population had a high prevalence of myopia (82.5%) and anisometropia (34.7%). Head tilt was a significant risk factor for anisometropia (OR = 1.71, p = 0.013) and correlated with differences in spherical equivalence (SE) and axial eye length. Shoulder imbalance was initially associated with SE (β = −0.48, p = 0.030) and axial length (β = 0.24, p = 0.025), but became nonsignificant after adjustment for parental myopia and lifestyle (n = 258). In the sensitivity analysis, the association of head tilt with anisometropia remained significant (OR = 1.94, p = 0.049). Forward head posture had no association with refractive parameters. Asymmetric deviations of body posture, especially head tilt, have associations with anisometropia. The findings highlight the value of postural assessment in the treatment of myopia.