Amidst growing emphasis on sustainability in the hotel industry, hotels are increasingly adopting sustainable practices. This trend extends to online platforms, where hotels showcase their sustainability labels as a form of advanced Corporate Social Responsibility (CSR). Such CSR communication is crucially influenced by how customers perceive the consistency of a hotel’s CSR efforts. In the sphere of online hotel booking, customer reviews play a pivotal role as other external clues, illustrating how well hotels fulfill their fundamental economic responsibility. Our study aims to investigate the interactive effects between hotel sustainability labels and the valence of online reviews on customers’ booking intentions. Based on attribution theory and several experimental studies, this research reveals that in the context of negative hotel review valence, the presence (vs. absence) of sustainability labels decreases customers’ booking intention due to an increase in perceived hypocrisy towards the hotel; conversely, in the context of positive hotel review valence, the presence (vs. absence) of sustainability labels enhances customers’ booking intention due to an increase in perceived morality towards the hotel. These findings contribute to the literature exploring hotel sustainability labels, online hotel reviews, and perceptions of hotel hypocrisy.