Reductive transformation of CO2 using green hydrogen or methanol enables the production of industrially significant chemicals such as carboxylic acid esters, which, however, is hindered by the dependence on noble metal catalysts and the use of halide additives. Here we report a robust non-noble metal-based, halide-free catalytic system for the reductive methoxycarbonylation of ethylene with CO2/MeOH. This system achieves a turnover number of up to 110 for methyl propionate, a key precursor in polymethyl methacrylate production, showing a better performance than conventional noble-metal-based systems. Remarkably, the present system exhibits moderate performance under simulated flue gas containing NOx and SOx, demonstrating the potential for in situ CO2 capture and conversion into value-added chemicals, promoting green and sustainable development.The success of the strategy lies in the unprecedented in situ formation and alcoholytic ring-opening of a five-membered nickelalactone, effectively bypassing the conventional but challenging CO2-to-CO-carbonylation pathway. Notably, this protocol offers a process free from noble metals, halide/acid additives, and strong/expensive reductants, for the production of next-generation CO2-based polymers.