Interfacial failure under electro-mechanical coupling critically limits the reliability of conductive greases. To overcome graphene restacking and reduce the chemical damage risk associated with ionic liquid-modified systems, polypyrrole/graphene (G/PPy) and polybenzimidazole/graphene (G/PBI) nanocomposites were synthesized via in situ polymerization and evaluated under current-carrying sliding conditions. Compared with the PAO40 base grease, G/PPy showed the largest relative reduction in electrical contact resistance (ECR). Its stable ECR decreased by 57.4%. Among the tested systems, G/PBI exhibited the lowest average coefficient of friction, with the value reduced to 0.0972. Its specific wear rate decreased by 38.2% relative to the base grease. The non-seizure load of G/PBI reached 1050 N. Raman and XPS analyses indicate that the improved behavior of G/PBI is associated with the formation of a more stable composite tribofilm containing retained carbonaceous species and nitrogen-containing interfacial species. In particular, the higher relative Fe–N contribution in the G/PBI-lubricated wear track is consistent with more favorable nitrogen-related interfacial coordination, rather than serving as standalone proof of a unique anchoring pathway. These results suggest that regulating the molecular configuration of nitrogen-containing graphene nanocomposites can improve current-carrying lubrication by balancing friction reduction, wear resistance, electrical contact preservation, and interfacial chemical stability.