Sustainable practices are becoming increasingly important to tourists and hotel guests. As a result, destinations, hotels, and booking platforms are implementing eco-friendly practices and displaying sustainable badges to communicate their efforts to guests. While the use of sustainable badges increases the visibility of eco-friendly hotels, it is unclear whether they actually influence guests’ choices. This study aimed to explore the effects of the presence of sustainable badges and the awareness of sustainable practices on tourists’ attitudes and behavioral intentions using an experimental design. People who previously used a hotel-booking platform were randomly assigned to four hotel-booking scenarios with the manipulated presence of sustainable badges and awareness about sustainable practices on the website. The data analysis techniques included an analysis of variance, moderation, and a mediation analysis. The study’s results provided empirical evidence that the presence of a sustainable badge could have a positive impact on guests’ attitudes toward a hotel and intentions to book a hotel. These results contributed to the body of knowledge on the impact of sustainable practices, addressed an attitude–behavior gap between tourists’ attitudes and behavioral intentions, and provided valuable insights for destination management organizations, hotel managers, booking platforms, and policymakers interested in promoting sustainable tourism practices.