The self-initiation reaction of alkyl acrylates at high temperatures is known and allows the use of less thermal initiators to synthesize purer and more defect free products. The following computational study is paired in collaboration with reports of a strategy to increase the conversion of n-butyl acrylate (nBA) with participation of aerial oxygen as an initiator-catalyst agent. These results obtained by the incorporation of molecular oxygen in nBA polymerization resulted in a high conversion of monomers in a very short time without any consumption of conventional initiator. First-principles calculations based on density functional theory (DFT) reveal that a triplet diradical intermediate arises from solvated oxygen reacting with an acrylate monomer and can then mingle with another monomer to proceed towards polymerization. Molecular oxygen can then leave by thermal dissociation, serving as a true catalyst. Oxygen-initiation is contextualized with self-initiation mechanisms, demonstrating rate constants 7 orders of magnitude higher. This study opens a new path to redesign free-radical polymerization of nBA to make this process more economical and also to define the thermal dependence of oxygen’s catalytic and inhibitory role in free-radical polymerization.