Pickering emulsion stabilized by pH-reversible chitosan is developed to prepare degradable polymer microspheres by emulsion photopolymerization, where chitosan acts as a green and recyclable particulate emulsifier. The thiol–ene photopolymerization of trimethylolpropane tris(3-mercaptopropionate) and trimethylolpropane triacrylate is initiated by UV irradiation. Chitosan adsorbed at the surface of the microspheres can be recycled for polymerization at least three times. Moreover, ibuprofen (IBU) is loaded into the microspheres. The higher the release temperature or pH value, the faster release rate and higher release extent of IBU from the microspheres are found. Meanwhile, the resulting microspheres exhibit a good degradability in 1 M NaOH aqueous solution, with a weight loss of about 90 wt% after 35 days. This study demonstrates a potential green and recyclable application of chitosan in fabrication of degradable polymer microspheres.