Supramolecular co-assembly provides a brand-new powerful strategy for regulating simple organic molecules into various hierarchical nano- and microstructures as smart functional materials. In particular, chiral supramolecular assemblies with strong fluorescent emission have received extensive attention for their application as circularly polarized luminescence (CPL) emitters. Herein, we synthesized three achiral pyrene derivatives, but only the chiral co-assembly (R/S-NMe2-Py-2) can exhibit the regular and orderly helical nanofiber via π-π stacking interaction between chiral N,N'-dimethyl-binaphthyldiamine enantiomers (R/S-NMe2) and the achiral pyrene derivative (Py-2). Interestingly, this kind of 2:1 molar ratio (R/S-NMe2)2-Py-2 co-assembly with a helical nanofiber structure can emit a strong deep blue CPL signal from the achiral pyrene-based emitter, and the dissymmetry factor gem value can reach 0.027 (λem = 423 nm) in the film from spin-coating.