Iodine transfer (co)polymerization (ITP) was employed to form polyethylene (PE) and poly(ethylene-co-vinyl acetate) (EVA). ITPs were conducted at 80 bar pressure of ethylene in dimethylcarbonate (DMC) at 70 °C using tri- and tetra-iodofunctionalized chain transfer agents (CTAs) leading to secondary reinitiating radicals. To better comprehend their behaviour, a full study was undertaken to compare the kinetics, the structures of the final polymer and the molar mass control obtained when using analogous iodo and di-iodo CTAs leading to the same secondary reinitiating radials. Well-defined linear PEs carrying one or two iodo chain ends could be formed together with three- and four-arm star PE. The possibility to cleave each arm of the corresponding star structures allowed to show good control of the polymerizations. The transposition to the copolymerization of ethylene and vinyl acetate led to the formation of well-defined four arm star EVA.