In the context of rising food costs, low-income consumers are likely to lack financial access to a sustainable diet primarily composed of healthy plant-based food. To promote a change towards more sustainable food habits, vouchers for fruit, vegetables and legumes redeemable in supermarkets have been experimented in the urban area of Dijon (France). The objective of the study was to explore the acceptability of the intervention and the effects of the vouchers on food choices through participants' perceptions. Face-to-face semi-structured interviews were conducted with twenty-seven participants, three months after the end of the intervention. The transcripts were analysed through inductive then deductive content analysis, following a process evaluation framework with two themes related to the implementation and the mechanisms of impact of the intervention. Implementation issues and feelings of discrimination were mentioned, but satisfaction was high and vouchers were considered to improve the financial situation, although the restriction on the targeted products was not always understood. Regarding the mechanisms of impact, during the intervention period, two third of the participants, especially families with young children, attached greater importance to taste and curiosity for unfamiliar food and lesser importance to price. Vouchers thus led to food purchases of higher diversity and higher enjoyment. Other participants did not change their habits, mostly because of an improper use of the vouchers or the absence of motivation for a dietary change. These findings suggest that financial incentives not only increase access to sustainable food, but also influence food choice processes and contribute to greater acceptability of plant-based food in low-income families. The results call for financial incentives to be considered as an opportunity to support changes in dietary behaviour in low-income populations.