<p>Consumers are increasingly concerned about both the freshness and low-carbon levels of fresh products, driving enterprises to invest in freshness-keeping and carbon emission reduction efforts. Moreover, the government has formulated policies to regulate emissions and support freshness-keeping. In practice, fresh-product firms often face capital constraints and must rely on external financing to support their operations. Against this background, this paper examines the joint operational and financing decisions of fresh-product firms within the context of supply chain financing. We develop models that capture both consumer preferences for low-carbon products and a mixed carbon trade market (with government subsidies and carbon allowances). Two financing scenarios are analyzed: bank financing and equity financing. We compare the optimal decisions under different scenarios and conduct several numerical studies to validate theoretical findings and explore firms’ optimal financing strategies. The results indicate that equity financing improves firms’ operational efforts, thereby achieving significantly greater carbon emissions reductions and superior environmental performance. In contrast, the bank financing yields the weakest environmental performance since it is associated with the highest carbon emission level. Moreover, under equity financing, the profit-sharing proportions influence pricing decisions and may lead to retail prices falling below wholesale prices. Under bank financing, the effect of carbon trading price on the supplier’s carbon reduction effect is non-linear. Finally, we also reveal that the mixed carbon policy can effectively improve the supply chain economic efficiency and promote social sustainability.</p>