• This study introduces a novel biodegradable water-soluble multipurpose polymer– polyethylene glycol (PEG) grafted pseudo-proteins (PP) using a simple and cost-effective approach. • Polymer-analogous Michael addition reaction with methoxy-PEG-thiol and methoxy-PEG-amine generates amphiphilic PEG-PPs, which are water-soluble and self-assemble into micelles. • The PEG-PPs stabilize the nanoparticles prepared from homo-PP of poly(ester amide) class via the nanoprecipitation method, coating them with a protective PEG cloud. • The fabricated nanoparticles are suitable for drug delivery and other biomedical applications. Amphiphilic biodegradable polymers are of great interest as resorbable micellar drug delivery vehicles, surfactants, and protective coatings for nanoparticles (NPs) providing stealthy properties in vivo, to name a few. The main goal of the present study is the preparation of novel biodegradable water-soluble multipurpose polymers- polyethylene glycol (PEG) grafted pseudo-proteins (PP) using a simple and cost-effective approach. The biodegradable PEG grafted PPs (PEG-PPs) of the poly (ester amide) (PEA) class were synthesized using a two-step procedure: the interfacial polycondensation of bis-nucleophilic monomer (L6) with a mixture of bis-electrophilic monomers − 1/1 (mole/mole) mixture of fumaryl chloride/sebacoyl chloride at the first step, leading to the formation of the unsaturated precursor − co-poly(ester amide) (FuL6) 0.5n -(8L6) 0.5n followed by a further polymer-analogous Michael addition reaction with methoxy-PEG-thiol and methoxy-PEG-amine at the second step. In contrast to the hydrophobic precursor, co-poly(ester amide) (FuL6) 0.5n -(8L6) 0.5n , the resulting amphiphilic PEG-PPs are water-soluble and, similar to traditional surfactants, form micelles with a size ranging from 20.4 to 51.6 nm, and a polydispersity index ranging from 0.104 to 0.305. The biodegradability of the synthesized polymers was evaluated in situ under enzymatic conditions using α-chymotrypsin. The PEG-PPs stabilized the pseudo-protein NPs prepared from the homo-PEA 8L6 by the nanoprecipitation method, simultaneously coating them with a protective PEG cloud. The fabricated NPs had an average diameter of 132.2–176.0 nm and a dispersity index within 0.147–0.273. Furthermore, antimicrobial agent Triclosan was encapsulated inside the 8L6 NPs and the antibacterial potential was tested against Staphylococcus aureus and Escherichia coli . Inhibition zone assays demonstrated clear antibacterial activity, highlighting NP suitability for drug delivery applications.