In spite of their high potency and specificity, few protein drugs have advanced to the clinical settings due to lack of safe and efficient delivery vehicles. Here, novel anisamide-decorated pH-sensitive degradable chimaeric polymersomes (Anis-CPs) were designed, prepared, and investigated for efficient and targeted delivery of apoptotic protein, granzyme B (GrB), to lung cancer cells. Anis-CPs were readily prepared with varying Anis surface densities from anisamide end-capped poly(ethylene glycol)-b-poly(2,4,6- trimethoxybenzylidene-1,1,1-tris(hydroxymethyl)ethane methacrylate)-b-poly(acrylic acid) (Anis-PEG-PTTMA-PAA) and PEG-PTTMA-PAA copolymers. Using cytochrome C (CC) as a model protein, Anis-CPs displayed high protein loading efficiencies (40.5-100%) and loading contents (up to 16.8 wt %). CC-loaded Anis-CPs had narrow distribution (PDI 0.04-0.13) and small sizes ranging from 152 to 171 nm, which increased with increasing CC contents. Notably, the release of proteins from Anis-CPs was accelerated under mildly acidic conditions, due to the hydrolysis of acetal bonds in PTTMA. MTT assays showed that GrB-loaded Anis-CPs (GrB-Anis-CPs) displayed high targetability to sigma receptor overexpressing cancer cells such as H460 and PC-3 cells. For example, GrB-Anis-CPs exhibited increasing antitumor efficacy to H460 cells with increasing Anis contents from 0 to 80%. The antitumor activity of GrB-Anis-CPs was significantly reduced upon pretreating H460 cells with haloperidol (a competitive antagonist). Notably, the half-maximal inhibitory concentrations (IC50) of GrB-Anis70-CPs were determined to be 6.25 and 5.94 nM for H460 and PC-3 cells, respectively, which were 2-3 orders of magnitude lower than that of chemotherapeutic drugs, such as paclitaxel. Flow cytometry studies demonstrated that GrB-Anis70-CPs induced widespread apoptosis of H460 cells. The confocal laser scanning microscopy (CLSM) experiments using FITC-labeled CC-loaded Anis-CPs confirmed fast internalization and intracellular protein release into H460 cells. GrB-Anis-CPs with high potency and specificity are particularly interesting for targeted therapy of lung cancers.