Electrochemically mediated atom transfer radical polymerization (eATRP) was investigated for synthesis of star polymers using macroinitiators (MIs), achieving high star yield with low Cu catalyst loading (∼100 ppm, w/w). The arm first method, using MIs, is one of the most robust procedures for star polymer synthesis. During the polymerization, MIs can react with cross-linkers (divinyl or multivinyl compounds) for initial chain extension followed by the cross-linking reaction. The MIs can be transformed to arms of the star, and the cross-linker can form the star core. In this study, poly(ethylene oxide) (PEO, Mn = 2000) based MIs (PEO MIs) were prepared, and the chain-end functionalities were confirmed by 1H NMR analysis. The ATRP functionalized PEO MIs were then used for the star synthesis by reacting with ethylene glycol diacrylate cross-linkers. Various experimental conditions were conducted for optimizing star formation, including MI concentration, MI to cross-linker molar ratio, and applied potential (Eapp).