Voice assistance (VA) has been widely adopted in the tourism and hospitality industry to interact and communicate with tourists and provide useful travel recommendations. Although more companies in tourism have adopted environmental sustainability practices and tourists have increased their sustainability awareness, lack of research has been conducted to investigate the effectiveness of VA in promoting sustainable consumption of tourism products or services. This study proposes that customising environmental sustainability messages for tourists with different cultural orientations and VA use purposes can enhance their engagement with the VA, which can affect their consumption decision. The results from a scenario-based experiment demonstrate that tourists with interdependent/independent cultural orientation have higher engagement with the environmental sustainability messages communicated by the VA when they are with a non-transactional/transactional purpose. Implications for tourism marketing strategies are discussed.