Background: This study aimed to understand parents' concerns about their adult child with intellectual disabilities due to the restriction of community-based services amid the COVID-19 pandemic in South Korea. Methods: In-depth interviews were conducted face-to-face or by telephone with 19 parents of adult children with intellectual disabilities who had to stop using community-based services. Results: Participants worried that their adult child was not aware of the seriousness of COVID-19, was more susceptible to the COVID-19 virus, could not recognize self-infection and could have fatal consequences of getting infected with COVID-19. They expected challenges in their adult child's life (losing a daily routine, being isolated, regression in skills, becoming bored, lacking physical activities and increased behavioural challenges) but also experienced adjustments and hopes. Conclusion: The study demonstrated parents' worry about their adult child becoming infected with COVID-19, highlighting the urgent need for community-based services to address psychosocial challenges during the pandemic.