The applications of materials are closely associated with surface structures and properties. Surface coassembly of block copolymers (BCPs) and polymer brushes is an effective method to fabricate surface structures with tunable properties. The surface coassembly approach not only provides a method for the fabrication of surface structures but also provides a method for the synthesis of hybrid materials with hierarchical nanostructures. In this research, polystyrene (PS)-assisted fusions of PS brushes on silica particles and BCP vesicles in a surface coassembly process are studied. The concentrations of BCP and PS homopolymer are two key parameters in the fusion process. When the BCP concentration is held constant at 3 mg/mL, with an increase in PS concentration, aggregation of silica particles and the fusions of polymer brushes and BCP vesicles are observed. When the BCP concentration is kept at 8 mg/mL, large hybrid compound structures composed of silica particles and the fused vesicles are formed. In the surface coassembly process, the addition of PS leads to an increased volume percentage of the solvophobic component in the system. To reduce the surface energy and the unfavorable contact between the solvent and PS, silica particles with PS brushes and BCP vesicles are fused into large compound structures. A variety of hybrid materials with hierarchical macro-/mesostructures can be fabricated by using this method.