The micellization behavior of linear ABC terpolymers containing a solvophobic block in the middle, accompanied by solvophilic and thermoresponsive blocks at the ends, is studied by means of Brownian dynamics simulations. The effects of the length of the thermoresponsive moiety on the shape and size of aggregates, formed as the temperature of the solution reduces and solvent progressively becomes bad for the thermoresponsive block, are studied in detail. Two crossover temperatures, T* = 2.4 and T* = 2.0, were found. The first one corresponds to the formation of loose aggregates and the second one to regular micelles. At both solution temperatures, as the thermoresponsive block length increases, a shape transition from spherical to segmented worm-like and back to spherical loose aggregates or micelles was observed. Our results are compared with recent experimental findings of similar systems.