Hybrid monoliths, which is expected to combine the merits of the organic polymer and inorganic silica-based monoliths, such as easy preparation, high permeability, pH tolerance and mechanical strength, and have attracted substantial interest in a large variety of fields, especially as separation media in liquid chromatography. In order to match variety of specific separations, numerous hybrid monoliths with different surface properties are needed. However, due to the diversity of precursors, it is time-consuming and laborious to prepare different kinds of hybrid monoliths. Post-modification of the synthesized monoliths seems a good option. Here we present a novel, functionalizable porous hybrid monolith via ring-opening polymerization with polyhedral oligomeric silsesquioxanes (POSS) and poly(ethylenimine) (PEI). Benefiting from the moderate phase separation process, the obtained hybrid monolith possessed well-defined 3D skeletal structure, exhibited high column efficiencies when respect to capillary liquid chromatography (cLC) application. Besides, the introduction of POSS monomer and PEI endowed the hybrid monolith high robustness and good tailorbility, thus, chemical modification of γ-gluconolactone and physical coating of cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) were performed on which, respectively. The former was successfully applied for HILIC separation of neutral, basic and acidic polar compounds as well as small peptides, and the latter for enantioseparation of racemates in cLC. The high column efficiencies were achieved in all of those separations. These results demonstrated that the hybrid monolith (POSS-PEI) possessed high stability and good surface tailorbility, potentially being applied for other research fields.