Polymerization‐induced self‐assembly (PISA) enables the synthesis at large scale of a wide variety of functional nanoparticles. However, a large number of works are related to controlled radical polymerization (CRP) methods and are generally undertaken at elevated temperatures (>50 °C). Here is the first report on methacrylate‐based nanoparticles fabricated by group transfer polymerization‐induced self‐assembly (GTPISA) in non‐polar media ( n‐ heptane). This GTPISA process is achieved at room temperature (RT) using 1‐methoxy‐1‐(trimethylsiloxy)‐2‐methylprop‐1‐ene (MTS) and tetrabutylammonium bis‐benzoate (TBABB) as initiator and organic catalyst, respectively. Under these conditions, well‐defined metal‐free and colorless diblock copolymers are produced with efficient crossover from the non‐polar stabilizing poly(lauryl methacrylate) (PLMA) block to the non‐soluble poly(benzyl methacrylate) (PBzMA) segment. The resulting PLMA ‐b‐ PBzMA block copolymers simultaneously self‐assemble into nanostructures of various sizes and morphologies. GTPISA in non‐polar solvent proceeds rapidly at RT and avoids the use of sulfur or halogenated compounds or metallic catalysts associated with the implementation of CRP methods, thus expanding the potential of PISA formulations for applications in non‐polar environments.