Metal-organic frameworks (MOFs), also known as porous coordination polymers, are a class of crystalline porous materials consisting of metal ion nodes held together by multitopic organic ligands. Among MOFs, Cu-BTC is a well-studied benchmark MOF. In practical applications, supported porous and stable MOFs on the surface of nanofibers, which provide a high specific surface area and prevent aggregation of the microstructure, may be very useful. This paper reports a facile strategy for the synthesis of core-shell polyimide/Cu-BTC hierarchical nanofibers by combining electrospinning, step-by-step seeding, and hydrothermal process. The Cu-BTC nanocrystals can be well immobilized onto the surface of polyimide nanofibers. The hierarchical nanofibers exhibited high gas separation and adsorption of methylene blue from aqueous solution.