Thermoresponsive polymers have recently attracted considerable interest as macromolecular chain transfer agents in RAFT emulsion polymerizations to prepare nanoparticles with tuneable cores, sizes, shapes or surfaces. So far, this synthesis technique requires the use of a conventional surfactant as a stabilizer (e.g., sodium dodecyl sulphate), thus limiting its scope and potential applications. Here, we report the surfactant-free RAFT emulsion polymerization using, for the first time, a biocompatible thermoresponsive polymer as a dual macromolecular chain transfer agent and a macromolecular stabilizer. By randomly incorporating a hydrophilic component with ∼21 ethylene glycol units on the side chain, we synthesized a series of novel thermoresponsive copolymers that can form self-stabilized particles upon heating above their cloud point temperatures. These novel thermoresponsive copolymers have been successfully used to produce nanoparticles with tuneable shapes and cores, paving the way for the high-scale synthesis of biocompatible nanoparticles with complex nanostructures and tailored properties.