This study examined the effects of the COVID-19 pandemic on the gambling behavior of individuals who were already actively engaged in such pursuits. We aimed to uncover the intricate consequences of the pandemic on this specific demographic, emphasizing the importance of understanding the complex connection between public health concerns such as the COVID-19 pandemic and gambling behavior from a public health perspective. In addition to identifying immediate impacts, this study holds significance in assessing potential long-term public health implications for the broader gambling industry. This study investigated how the COVID-19 pandemic has affected the gambling behavior of Mainland Chinese tourists in Macau from a public health perspective. We aimed to understand the changing patterns of gambling habits within this specific demographic by comparing their behavior before and during the pandemic, with a particular emphasis on the evolving dynamics of gambling and their public health consequences. This study provides a detailed exploration of the impact and implications of global health emergencies on this particular demographic's gambling behaviors and preferences. This study used a robust cross-sectional analysis involving a sample of 334 Mainland Chinese gamblers with prior experiences in casinos in Macau. The sample deliberately encompassed individuals involved in gambling before and during the COVID-19 pandemic. Data were collected through carefully designed questionnaires to gather information on gambling habits, preferences, and observed behavioral changes in the sample. This study unveiled a notable shift in Mainland Chinese gamblers' behavior during the COVID-19 pandemic. A considerable number of participants opted for web-based platforms over traditional land-based casinos, resulting in reduced budgets, less time spent on gambling, and decreased participation in social gambling. Remarkably, there was a notable surge in online gambling, indicating a noteworthy adaptability of gamblers to changing circumstances. These findings emphasize the dynamic nature of gambling habits during global public health emergencies, revealing the resilient and evolving preferences of Mainland Chinese gamblers in response to the challenges posed by the pandemic. This study highlights the negative impact of the COVID-19 pandemic on casino gambling, notably evident in a significant decline in Mainland Chinese tourists visiting Macau for gambling. There is a noticeable shift from traditional gambling to web-based alternatives, with individuals seeking options within the pandemic constraints. Furthermore, the findings point out an increase in gambling among the younger generation and behavioral changes in individuals with mood disorders. The findings of this study emphasize the critical need for proactive measures to address evolving gambling preferences and associated risks during public health crises; furthermore, these findings underscore the importance of adaptive strategies within the gambling industry, as well as the necessity for effective public health interventions and regulatory frameworks to respond to unprecedented challenges with efficacy and precision.