This study explores the electromagnetic properties of slowly rotating magnetized neutron stars within Modified Gravity (MOG), focusing on their plasma magnetospheres. Building on vacuum solutions of Maxwell’s equations by Deutsch and Rezzolla, it incorporates plasma effects as per Goldreich and Julian, analyzing charge-separated plasma and electric field amplification. Analytical solutions for the Goldreich-Julian charge density, adjusted for MOG parameters, reveal enhanced magnetic field components and potential pulsar jet formation. The influence of the MOG parameter α on polar cap geometry is investigated, bridging theoretical models with astrophysical observations. These findings offer new insights into the interplay of gravitational theories and pulsar electrodynamics.