While bringing happiness to tourists and facilitating economic development, tourism has also had multiple negative impacts. To promote responsible tourist behaviours, some destinations have introduced a responsible tourist pledge on their official travel website. However, its application in a responsible tourism context is still not well understood. This research investigates the effectiveness of using a pledge to promote sustainable travel behaviours in tourists. An online experiment was conducted with a sample of 140 Canadian outbound travellers. Results illustrate that a pledge alone does not cause sustainable travel behaviours, instead finding that values are able to predict tourists’ responsible travel behaviours. Further, finding that the interaction of signing a pledge and participant self-transcendence value was found to influence the behavioural intention to support the local economy. The findings provide practical implications for destinations in selecting strategies to encourage sustainable travel behaviours as well as theoretical implications for future studies.