White‐light‐emissive organic micro/nanostructures hold exotic potential applications in full‐color displays, on‐chip wavelength‐division multiplexing, and backlights of portable display devices, but are rarely realized in organic core/shell heterostructures. Herein, through regulating the noncovalent interactions between organic semiconductor molecules, a hierarchical self‐assembly approach of horizontal epitaxial‐growth is demonstrated for the fine synthesis of organic core/mono‐shell microwires with multicolor emission (red–green, red–blue, and green–blue) and especially organic core/double‐shell microwires with radial red–green–blue (RGB) emission, whose components are dibenzog,pchrysene (DgpC)‐based charge‐transfer (CT) complexes. In fact, the desired lattice mismatching (≈2%) and the excellent structure compatibility of these CT complexes facilitate the epitaxial‐growth process for the facile synthesis of organic core/shell microwires. With the RGB‐emissive substructures, these core/double‐shell organic microwires are microscale white‐light sources (CIE 0.34, 0.36). Besides, the white‐emissive core/double‐shell microwires demonstrate the fascinating full‐spectrum light transportation from 400 to 700 nm. This work indeed opens up a novel avenue for the accurate construction of organic core/shell heterostructures, which provides an attractive platform for the organic integrated optoelectronics. Through regulating the noncovalent interactions between organic semiconductor molecules (|ECT, DgpC‐TCNB = −18.35 kcal mol−1| > |ECT, DgpC‐TFP = −13.45 kcal mol−1| > |Eπ–π, DgpC = −6.81 kcal mol−1|), a hierarchical self‐assembly approach of horizontal epitaxial‐growth is demonstrated for the precise synthesis of organic core/double‐shell microwires with radial red–green–blue (RGB) substructures for miniaturized white‐light sources (CIE 0.34, 0.36).