Abstract We incorporate field line curvature (FLC) scattering into a kinetic ring current model two‐way coupled with a global magnetospheric MHD model to investigate its role in SYM‐H prediction and global magnetospheric dynamics. FLC scattering reduces plasma pressure in regions where the ion gyroradius is comparable to the local FLC radius. This pressure reduction weakens magnetic tension, resulting in a more dipolar magnetic field configuration that, in turn, suppresses further FLC scattering. This self‐regulating feedback loop prevents excessive FLC scattering and mitigates the overestimation of ring current decay often found in models using empirical magnetic fields. We demonstrate that incorporating FLC scattering improves agreement with observed SYM‐H throughout the entire storm period. These findings highlight the importance of self‐consistent coupling between plasma dynamics and magnetic field configuration, offering enhanced predictive capability for space weather modeling.