The present invention relates to a thermoplastic resin, a method of preparing the same, and a thermoplastic resin composition including the same. A thermoplastic resin having superior latex stability and thermal stability and generating a small amount of gas during processing, and a method of preparing the thermoplastic resin are provided. In addition, a thermoplastic resin composition having superior mechanical properties, surface gloss, whiteness, gloss after retention, and heat discoloration after retention and a small content of residual total volatile organic compounds (TVOC), due to inclusion of the thermoplastic resin, is provided.