<p>Palm oil is widely used in Malaysia’s food industry and consumed by Malaysians. The amount of food wasted in Malaysia is enormous, with consumers significantly contributing through their food-buying and consumption practices. The palm oil industry emphasises sustainable production but overlooks palm oil-based food consumption. Due to their lower prices and frequent promotional offers, palm oil-based foods are particularly susceptible to impulse buying. Research has established that the big five personality traits significantly influence consumers’ impulse buying behaviour, which in turn can lead to food waste. While impulse buying has been identified as a strong predictor of food waste, its mediating role specifically in the relationship between personality traits and food waste behaviour remains largely unexplored. Studies on food waste have predominantly focused on conscientiousness, with limited research on other personality traits. This study examined the relationships between consumers’ big five personality traits, impulse buying and wasting of palm oil-based foods, as well as the mediating effect of impulse buying. Using convenience sampling, data were collected from 327 participants through an online survey questionnaire and analysed using partial least squares-structural equation modeling. The findings showed that neuroticism, conscientiousness, and agreeableness had significant relationships with impulse buying of palm oil-based foods and that impulse buying predicted food wastage. Furthermore, impulse buying mediated the relationships between neuroticism, conscientiousness, and agreeableness and wastage of these foods. This study provided valuable insights for reducing food waste and promoting sustainable palm oil-based food consumption, contributing to SDG 12 and SDG 2.</p>