Polyhedral oligomeric silsesquioxane (POSS)-coated nanodiamonds (NDs@POSS) were prepared via the amide formation between amine-functionalized POSS and oxygen-containing groups of NDs. The POSS structures grafted on the surface of NDs enable the NDs@POSS nanocomposites to be well-dispersed in organic solvents and polymers for multifunctional applications. The surface coating of NDs with POSS also bring other incidental advantages such as enhanced thermal stability and superhydrophobic of the NDs. NDs@POSS nanocomposites-embedded hybrid films based on polycarbonate and polyvinyl butyral were fabricated by solution blending methods, showing tunable refractive indexes in the range of 1.49-1.61. Furthermore, the powders of NDs@POSS were superhydrophobic with contact angle of water/air of 154 degrees. Liquid marbles formed by coating the water droplet with NDs@POSS were prepared, and the process intensification effects of the NDs@POSS-based miniature reactors for degradation of methylene and fabrication of Ag nanoparticles were also demonstrated, respectively.