Amphiphilic rod-coil diblock copolymers combining the conductive features of a conjugated polymer and nanoscale morphologies arising from micro-phase separation of dissimilar blocks are attractive as potential materials for electronic applications. The synthesis and properties are reported for a novel amphiphilic diblock copolymer containing a block of regioregular poly(3-hexylthiophene) (P3HT) and poly(methyl methacrylate-random-2-hydroxyethyl methacrylate) (P(MMA-r-HEMA)) as the hydrophilic block. Well-defined rod-coil P3HT-b-P(MMA-r-HEMA) amphiphilic diblock copolymers with molar masses of around 11,000 and low molar mass dispersities (Đ M ) below 1.5 were successfully synthesized via the combination of quasi-living Grignard metathesis (GRIM) polymerization and atom transfer radical polymerization (ATRP). P3HT was first obtained in a regioregular form with an average molecular weight of around 7,200 g/mol and Đ M below 1.3. Post-polymerization end-group modifications of the asobtained P3HT were then successfully realized to give a macroinitiator for the ATRP of MMA and HEMA co-monomers, resulting in the P3HT-b-P(MMA-r-HEMA) diblock copolymers. The structure and properties of the resulting diblock copolymers were characterized by proton nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectroscopy, UV-visible spectroscopy and modulated differential scanning calorimetry (MDSC).