Peptide-polymer conjugate consisting of a sequence-defined tripeptide and poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) is synthesized by a simple grafting from atom transfer radical polymerization (ATRP) approach. The ATRP of PDMAEMA using peptide-macroinitiator and CuBr/1,1,4,7,10,10-hexamethyltriethylenetetramine system in anisole follows pseudo first order kinetics up to a conversion of about 25% within a time span of 125 min. The attachment of peptide moiety at the end of PDMAEMA chain is confirmed from MALDI-TOF-MS and circular dichroism analyses. The self-assembly of as-synthesized peptide-PDMAEMA conjugate in organic solvents leads to the formation of spherical nanoparticles as observed through FESEM. Peptide-PDMAEMA conjugate become soluble in water due to the protonation of the pendent N(CH3)(2) moiety of DMAEMA group of the conjugate. Owing to the amphiphilic nature of the protonated conjugate (peptide-PDMAEMAH), it also undergoes self-aggregation in water into nanostructures of various morphologies such as dendrite, small sphere and large sphere at pHs of 2, 8, and 10, respectively. Peptide-PDMAEMA-IBu conjugate obtained by the post-modification of N(CH3)(2) moiety of DMAEMA group of the conjugate with n-butylbromide also undergoes self-aggregation into dendritic nanostructures in water. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3286-3297