BACKGROUND: The COVID-19 pandemic was a major public health crisis, especially among older people. This study aimed to examine factors affecting preventive behaviors among community-dwelling older adults across all regions of Thailand during the COVID-19 pandemic using the health belief model (HBM). METHODS: This cross-sectional study included 910 participants from Thailand in July and August 2021. A multistage stratified random sampling technique was used to select participants. Data were collected through a structured interview process. Data analysis was conducted using multiple linear regression. RESULTS: The participants' mean age was 66.5 ± 4.64 years, with the majority being female (61.8%) and residing in the central region (26.5%). The results indicated that all participants (100.0%) agreed that COVID-19 can be prevented by personal protective equipment, such as masks and disposable gloves. Furthermore, the participants' adherence to COVID-19 preventive measures was evaluated, revealing that the majority (55.8%) always practiced hand hygiene by washing hands with alcohol gel or soap and cleaning them with water before eating. Regression analysis indicated that COVID-19 preventive behaviors were significantly associated with knowledge ( CONCLUSIONS: Increased knowledge, perceived susceptibility, perceived benefits, cues to action, and decreased perceived barriers scores were associated with higher practice scores among community-dwelling older adults during the COVID-19 pandemic in Thailand. To improve practices, health information campaigns should focus on highlighting the advantages of preventive behaviors, offering tips and advice to overcome barriers, providing cues to action through various reminders on social media, and increasing awareness about disease prevention and control in future pandemics or new disease outbreaks.