Government and corporate policies have mandated a reduction in plastic packaging to combat issues of waste and climate change. This move towards sustainable packaging alternatives in the fresh food sector will increase costs for consumers. Much of the present research finds consumers are willing to pay more for sustainability, but their willingness to pay (WTP) does not align with real-world purchases, representing an attitude–behaviour gap. To combat this gap, it is posited that consumers’ current purchasing- and sustainability-related behaviours will meaningfully correlate with their WTP and bridge the attitude–behaviour gap. This research used an online survey (n = 476) to gauge consumers’ attitudes and behaviours regarding sustainability as it relates to packaging, biofortification, and WTP in the fresh leafy greens sector. Using binary logistic regression, this research finds that price- and sustainability-related purchasing habits and attitudes towards sustainable packaging meaningfully narrow the attitude–behaviour gap, but organic purchasing habits, waste segregation habits, and sustainability literacy do not. This research contributes the knowledge that, for environmentally friendly leafy greens, past price- and sustainability-related purchasing behaviour should be used instead of merely attitudes as an indication of WTP.