An elegant integration of primary amine-bearing segments into the acrylic acid-containing blocks and the subsequent addition of silver nanoparticles (Ag NPs) to this double hydrophilic block copolymer endowed the resulting well-defined self-assembled construct with promising antimicrobial and anti-quorum sensing activity and high cytotoxicity against breast cancer cells. Poly(N- vinylformamide) (PNVF), precursor of amphoteric poly(vinyl amine) (PVAm), was chain-extended from pH-responsive poly(acrylic acid) (PAA) macro-chain transfer agent synthesized via reversible addition-fragmentation chain transfer polymerization by the interchange of xanthates (RAFT/MADIX). PAA-b-PNVF block copolymers with molecular weights in the range of 12500-21800 Da and dispersities between 1.29 and 1.44 were characterized by FTIR, elemental analysis,H- 1 and C-13 nuclear magnetic resonance (NMR) spectroscopy, and size exclusion chromatography (SEC). PAA-b-PVAm copolymer was obtained by hydrolysis of the PNVF block. The decoration of PAA-b-PVAm with monodisperse Ag NPs to yield AgNPs@PAA-b-PVAm proceeded through a simple and green approach by amine-induced reduction of Ag ions in aqueous media. The formation of AgNPs@PAA-b-PVAm was characterized by UV/vis spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). AgNPs@PAA-b-PVAm displayed superior antimicrobial and anti QS activity. The cell proliferation was tested with an MTT assay on L929 and MCF-7 cell lines. Both the AgNP-decorated and the bare copolymer showed significantly higher cytotoxicity on cancer cells compared to healthy ones.