This qualitative descriptive study aimed to explore dietary habits among healthcare workers during night shifts and to identify individual and environmental factors that influence their dietary behaviour during night shifts. Individual semi-structured interviews were conducted with twenty-five healthcare night female workers, which were recruited via email invitations from managers and posters placed in central workplaces at a university medical centre in the Netherlands. The interview protocol was developed following an integrated behaviour change model focusing on individual (I-Change model, i.e., awareness, motivation, intention, and ability) and environmental (Environmental Research framework for weight Gain prevention at environmental level (EnRG), i.e., physical, policy-related, economic, and sociocultural) factors. Inductive analyses were conducted to explore dietary habits, while deductive thematic analysis was applied to identify potential factors influencing dietary behaviour. Female healthcare workers in night shifts generally made poorer dietary choices during night shifts than during other shifts. Seven key themes were coded for dietary behaviour. Based on the domains of the integrated behaviour change model, four individual and five environmental key themes were established, within which 41 sub-themes were coded. Key individual factors included awareness (i.e., lack of knowledge about timing and type of consumption) and motivation (i.e., attitude and efficacy to eat healthy). Critical environmental factors included physical and sociocultural work environment, organisation of work, and lack of organisational policies. To conclude, future dietary interventions for healthcare night workers should target both individual behaviours and the workplace environment, with an emphasis on raising awareness and enhancing organisational policies to promote healthy dietary habits.