Whispering-gallery-mode (WGM)-mediated light emission produces sharp and distinct resonant peaks, providing a unique spectral signature that is ideal for photonic barcoding and compact microtagging. However, existing photonic barcodes are typically limited to visible wavelengths, restricting their tagging potential. Achieving precise light-emission control across the entire Vis–near-IR (NIR) spectral range is challenging, particularly when using a single object composed of a single material. Herein, multicolor-emitting carbonized polymer microbeads (MECPMs) are synthesized on a gram scale by a facile and scalable hydrothermal process. These spherical microbeads, which contain extended π-conjugated polycyclic aromatic hydrocarbons within their microcavities, emit broadband light spanning the entire Vis–NIR spectrum. Owing to their excitation-dependent photoluminescence, a single MECPM can produce color-tunable WGM-based white-light emission across the Vis–NIR spectrum, thereby enabling the generation of both visible and invisible microbarcodes by adjusting the excitation wavelength. Compared with conventional polymer- or oxide-based microcavities, MECPMs demonstrate enhanced chemical stability in acids and organic solvents, excellent spectral tunability, and outstanding photonic encryption capabilities. Their environmentally friendly, metal-free “chameleonic” photonic functionality provides a robust platform for anticounterfeiting, microtagging, labeling, and next-generation photonic security systems. Additionally, this invention facilitates photonic encryption via information encoding and transmission across the Vis–NIR spectral range.