Background and Objectives: Children with disabilities (such as cerebral palsy, autistic spectrum disorder, and Down syndrome) are the most vulnerable and marginalized subset of the population, representing 2.7% of the total population of Saudi Arabia. The COVID-19 outbreak might have disproportionately affected children with disabilities, augmented their isolation, and induced severe disruptions to the services on which these children rely. Limited research has been conducted in Saudi Arabia to understand the impact of the COVID-19 pandemic on the rehabilitation services provided to children with disabilities and barriers. This study aimed to investigate the effect of the lockdown implemented as a result of the coronavirus disease-2019 (COVID-19) pandemic on the accessibility of rehabilitation services, including communication, occupational therapy, and physical therapy, in Riyadh, Kingdom of Saudi Arabia. Materials and Methods: In this cross-sectional study, a survey was conducted between June and September 2020 during the lockdown in Saudi Arabia. A total of 316 caregivers of children with disabilities from Riyadh participated in the study. The accessibility of rehabilitation services provided to children with disabilities was assessed by designing a valid questionnaire. Results: A total of 280 children with disabilities received rehabilitation services before the COVID-19 pandemic and showed improvement following therapeutic sessions. However, during the pandemic, most children stopped receiving therapeutic sessions because of lockdown, which deteriorated their condition. This shows a significant reduction in the accessibility of the rehabilitation services provided during the pandemic. Conclusions: The findings of this study revealed a drastic decline in services provided to children with disabilities. This caused a notable deterioration in the abilities of these children.