The solid-state hard encapsulation of carbon dots (CDs) can introduce an additional dimension for the tuning of their optical properties and effective promotion of multifunctional applications as well. In this study, simple hydrothermal and soft-sintering processes have been demonstrated to obtain silicon oxynitride-encapsulated N-doped carbon dots (SiON@NCDs) as well as organosilane-functionalized NCDs (OSi-NCDs). The surface-decorating long alkyl chains on NCDs help to prevent luminescence quenching in solid state and emit blue to orange color while forming a smooth film coating on the substrate. Interestingly, these OSi-NCDs can be readily converted into SiON-encapsulated NCDs (SiON@NCDs) and form a smooth, hard, and visible light transparent coating on a glass surface after soft sintering. This hard coating has the ability to emit white light and 100% block all types of toxic UV light (UV-A, B, and C). The process reported here provides a unique strategy to modulate the NCD luminance properties from blue to white light emission (WLE) by transforming the organosilane matrix together with the NCDs themselves, possibly modified at their surface defects or functional groups. The transformation process involves the conversion of organosilane into a SiON hard-coat matrix via the reaction with the amine surface groups on NCDs. Subsequently, the hard-coat-embedded NCD films emit WLE under UV excitation with good color stability and adjustable correlated color temperature (CCT) from warm white to cool white (3900-7300 K) depending upon their thicknesses. The process proposed here can be adopted for glass hard coating for white light emission (WLE) and UV-light blocking applications. Also, with our proposed hard encapsulation scheme, NCDs are endowed with long-term stability in harsh environmental conditions, which enables these materials for practical applications in many fields, including automotive, illumination industrial sectors, and luminescent solar cells (solar cell windows). © 2021 American Chemical Society