This study investigates the influence of artificial intelligence (AI) on consumer behaviour, focusing on personalised marketing and sustainable shopping practices. It addresses the gap in empirical research by examining how AI integration in personalised marketing can promote sustainable consumption. The research questions explore how AI changes online shopping consumer behaviour and influences sustainability attitudes. Using a quantitative methodology, data were collected from 139 adult consumers in Portugal. Results indicate that AI significantly improves the relevance and efficiency of personalised shopping experiences, promotes conscious consumption, and reduces waste. However, consumers still prefer human interactions over AI-automated processes during purchases despite the positive impact on sustainability. The findings suggest that while AI can drive sustainable consumer behaviour, there is a need for regulatory frameworks and green AI methodologies to mitigate its environmental impact and enhance consumer trust.