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Petroleum hydrocarbon-contaminated water remains difficult to remediate because crude-oil-derived pollutants are chemically diverse, hydrophobic, and persistent. Herein, a graphene nanoplatelet-integrated polymeric iron phthalocyanine framework (GNP-PFePc) was developed as an interfacial peroxydisulfate (PDS) activator for the removal and oxidative attenuation of total petroleum hydrocarbons (TPH) in crude-oil-contaminated water. The contaminated-water matrix contained an initial GC–MS-detectable TPH concentration of 11.47 g L⁻¹ dominated by C₁₁-C₂₉ linear and branched aliphatic hydrocarbons. GNP-PFePc integrates polymeric Fe-N-C domain containing Fe-N₄-type coordination environments with a conductive and hydrophobic graphene nanoplatelet scaffold, thereby enhancing active-site accessibility, hydrocarbon enrichment and localized PDS activation at the catalyst-water interfaces. Under optimized conditions, GNP-PFePc/PDS achieved 89.7 % TPH removal within 30 min and 94.9 % within 150 min. The apparent pseudo-first-order rate constant calculated over the 150 min reaction interval was 0.0198 min⁻¹, corresponding to 17.2-fold and 5.7-fold enhancements relative to PDS alone and GNP-PFePc alone, respectively. Control and kinetic analyses showed that the coupled system outperformed adsorption or direct PDS oxidation alone, supporting an adsorption-assisted interfacial oxidation pathway. Compound-resolved analysis further showed that parent-hydrocarbon removal and oxidative attenuation were structure-dependent, with different responses across linear, branched, long chain and halogenated hydrocarbon fractions. Radical-scavenging and surface-probe experiments indicated that SO₄•^⁻ and •OH participated in the oxidation process, with a substantial contribution from surface- reactive species generated at the GNP-PFePc/PDS interface. Overall, the results demonstrate that GNP-PFePc provides an effective Fe-N-C-type catalytic interface for localized PDS activation and surface-associated reactive oxidative- removal of petroleum hydrocarbons in crude-oil-contaminated water.