In this contribution we report the synthesis of hybrid poly(styrene-co-maleic anhydride)–SiO2 microcapsules by cross-linking of the stabilizing particles of an inverse Pickering emulsion droplet at the interface. This was achieved by the ring-opening aminolysis reaction of the maleic anhydride residue of poly(St-co-MAh) with amine-functionalized silica particles that stabilized the Pickering emulsion. The cross-linking reaction is clearly shown by labeling the polymer with a green dye and the silica particles with a red dye, followed by confocal fluorescence microscopy analysis. Because poly(St-co-MAh) is a versatile polymer that can react with different other polymers, this opens the possibility of producing microcapsules with versatile properties. Encapsulation of delicate matter, e.g., live cells or enzymes, might be suitable as a result of the straightforward synthesis method.