In two studies we tested for a relationship between consumption of a Western-style diet, characterised by high intakes of saturated fat and added sugar, and individual differences in impulsivity. In Study 1, participants completed both a food frequency measure to assess diet and a measure of trait impulsivity. Greater trait impulsivity was associated with consumption of a Western-style diet in both men and women, independent of body mass index (BMI). Greater intake of sugar-sweetened beverages and take-away food were specifically linked to greater trait impulsivity. In Study 2 lean participants completed a laboratory-based impulsivity battery. Habitually consuming a Western-style diet was associated with greater trait self-report urgency and with more impulsive behaviour on a food Delayed Discounting Task (DDT). Dietary relationships with trait sensation seeking, and performance on the Matching Familiar Figures Test, were moderated by gender. Dietary Restraint, disinhibition, and Hunger scores from the Three Factor Eating Questionnaire had only a small impact upon the relationship between a Western-style diet and impulsivity. These findings suggest that greater impulsivity is associated with consuming a Western-style diet, with possibly bidirectional causation.