In the present work, polymersomes based on self-assembled, folate-targeted, redox-responsive, ATRP-based amphiphilic diblock copolymer poly(polyethylene glycol)-S-S-polylactide with disulfide linkage were developed for efficient doxorubicin (DOX) delivery and compared with marketed DOXIL nanoformulation. The polymersomes formulation was optimized by quality by design approach providing monodisperse nanostructures of ∼110 nm and enhanced DOX loading of ∼20%. Polymersomes showed excellent stability as per the ICH guidelines over the extended storage period of 3 months. The in vitro drug release profile confirmed the redox sensitive behavior of polymersomes providing ∼80% drug release in endosomal pH 5 with 10 mmol GSH as compared to ∼20% release at pH 7.4. The targeted polymersomes achieved enhanced cellular internalization in folate receptor overexpressing cell lines, MDA-MB-231 and HeLa, providing ∼24% higher tumor reduction than DOXIL in Ehrlich ascites tumor bearing Swiss albino mice.