• • Xe lamp irradiation induces a substantial enhancement of magnetization in MVPB, MVPB-Co, and MVPB-Ni hybrids, with partial relaxation under prolonged exposure, demonstrating reversible photo-modulation.
• • The photomagnetic effect originates from MV2+ reduction to MV+• radicals, which act as spin carriers coupling to metal ion moments, decoupling the response from the inorganic lattice and eliminating sensitivity to stoichiometry.
• • The strategy is generalizable across different cyanide-bridged metal pairs, irrespective of alkaline cations, vacancies, or water content, addressing a key bottleneck in PBA photomagnetic design.
• • The observed decrease in coercivity and suppression of spin-glass behavior under irradiation indicate reduced energy barriers, confirming the dynamic role of MV+• radicals in modulating magnetic properties.