Emotions are predicted to influence judgement and decision-making across a range of performance contexts. This experiment tested whether motivational-general arousal imagery can improve the decision-making performance of elite endurance cyclists. In total, 54 cyclists (38 men, 16 women) were assigned to either a positive imagery condition (where positive images associated with the affective experience of winning were encouraged) or a negative imagery condition (where negative images associated with poor performance were encouraged). The cyclists were read one of two scripts designed to elicit positive or negative images during a 20-min maximal sustainable interval on a cycle ergometer. A decision-making task (colour–word match Stroop) was performed before and immediately after the maximal sustainable power interval. Results showed that the manipulation was successful with cyclists in the positive imagery condition reporting more positive affective states (higher levels of happiness and lower levels of dejection) than those in the negative imagery condition. However, there was no significant difference between the two groups in their decision-making performance under physiological duress. These findings indicate that while motivational-general arousal imagery might be a useful method to induce positive emotions during exercise, it is unlikely to improve the decision-making performance of cyclists in performance-relevant conditions.