Aim To investigate fear of COVID‐19 and related factors among Thai people living with HIV (PLHIV). Methods This cross‐sectional survey was conducted among 204 participants using an online convenience sampling method. Data were collected using a demographic characteristics form, the knowledge , attitudes , and practices toward COVID‐19 questionnaire, and the Fear of COVID‐19 scale (FCV‐19S). Data were analyzed using descriptive and inferential statistics. Results The sample consisted of 204 Thai PLHIV (47.1% female and 52.9% male). Knowledge level about COVID‐19 in 94.83% of the participants was acceptable, and 85.3% of them had confidence about successful control of COVID‐19 in Thailand; and 99.5% wore a mask when leaving home in recent days. Fear of COVID‐19 was at a mild level. COVID‐19 fear scores were significantly higher in those 60 years old and over, and those who had a family member or close friend who was sick due to COVID‐19. Knowledge and preventive practice were significantly related to FCV‐19S scores. Age, knowledge, and preventive practice regarding COVID‐19 were the influencing factors in fear of COVID‐19 (adjusted R 2 = 0.281, F = 6.221, p < .05). Conclusions COVID‐19 pandemic has significantly influenced fear among PLHIV. Our findings might be useful for healthcare professions to develop effective campaigns to minimize the fear of COVID‐19 in potential future pandemics.