Triboelectric nanogenerators (TENGs) have opened a new direction in the field of flexible devices. Here, a fluorescent TENG–JNA constructed with a flexible Janus nanobelt array (JNA) and PVDF/PVP nanofibers membrane by electro-spinning is reported for the first time. The building unit of JNA is the [PANI/CNTs/PMMA]//[Tb(BA)₃phen/PMMA] Janus nanobelts, which demonstrate green fluorescence and electrical conduction bi-function, where two independent partitions are microscopically realized in the Janus nanobelts. In TENG–JNA, JNA concurrently gains excellent charge-trapping ability and charge-generating capability by optimizing the PANI content; therefore, JNA serves as both a charge-generating layer and charge-trapping layer. The interface between TB(BA)₃phen and PMMA, the existence of aromatic ring structures in the PANI main chain and the interface between PANI and PMMA are conducive to trap a large number of triboelectric charges in time to prevent the triboelectric charges from combining with induced charges, which can significantly improve the output performance of TENG–JNA. The maximum output current and voltage of TENG–JNA are 6.20 μA and 155 V, respectively. The introduction of Tb(BA)₃phen ensures the strong fluorescence of TENF–JNA, and this fluorescence can be used to judge whether TENF–JNA works normally or is out of order in a dark environment. TENG–JNA possesses other compelling features, such as prominent flexibility, good hydrophobicity, durability and light weight, which provides the premise for TENG–JNA to be used as a flexible device in a wet environment or for warning functions. The Janus nanobelt was firstly used to assemble a TENG, which provides theoretical, material and technical support for the development of new building units of TENGs and paves a pathway for designing and assembling new TENGs.