Influential and trusted opinion leaders play a crucial role in society, particularly in influencing the public about values and lifestyle aspects. However, studies that have explored the impact of opinion leaders on a sustainable lifestyle and Islamic values in a Muslim-majority country such as Malaysia are scarce. Hence, this present study investigated the moderating effect of opinion leaders on the relationship between Islamic values derived from Maqasid Shariah and a sustainable lifestyle in Malaysia. The two methods deployed in this study were survey and in-depth interviews. Data retrieved from 682 questionnaires completed by Malaysian respondents were analysed using Smart PLS. The outcomes showed that, among the five proposed hypotheses, only one was accepted—the moderating effect of opinion leaders on the relationship between preserving intellect and a sustainable lifestyle. In-depth interview sessions were held with 18 respondents encompassing Islamic figures, environmentalists, and survey respondents. Most respondents claimed that the role of opinion leaders is important, and a healthy mind (preserving intellect) should be the priority to achieve a sustainable lifestyle. The study outcomes may serve as a reference for the Malaysian government to devise effective plans for sustainable lifestyle education by incorporating the Islamic framework.