We report herein the synthesis of silica-based carbon dots (CDs)/nanocrystal (NC) hybrids with white fluorescence and their application in white LEDs. First, silane-functionalized CDs with strong fluorescence (quantum yield = 20 %) were prepared by the hydrothermal method from citric acid and (3-aminopropyl) triethoxysilane (APTES). The optical properties of the CDs were thoroughly investigated, as well as the structural properties. Then silica-based CD/CdS NC hybrids emitting bright white light under UV excitation were realized by co-hydrolyzing the blue fluorescent CDs functionalized by APTES with yellow-emitting CdS NCs modified by (3-mercaptopropyl) trimethoxysilane (MPTMS). The hybrids show many merits, like excellent fluorescence, easy access, low cost, and good compatibility with silicone, suggesting that they could be promising candidates as white phosphors for energy-efficient optoelectronic devices. To realize their potential, a white light-emitting diode (LED) was finally fabricated by the as-prepared CD/CdS NC hybrids as converters, which exhibits white light with a color coordinate of (0.27, 0.32).