OBJECTIVES: COVID-19 infection increased nephrology-related risks and mortality rate among end-stage renal disease (ESRD) patients. The pandemic also disrupted essential healthcare services. We aim to explore all-cause excess mortality among ESRD patients who were members of the Universal Coverage Scheme (UCS), the largest public health insurance scheme in Thailand covering citizens who are not employed in the formal sector, including children and older persons. DESIGN: A cross-sectional study. SETTING: We retrieved the dataset from the UCS claims database-electronic health records used for processing healthcare expense claims from medical facilities of all UCS members. This database links mortality outcome to civil registration. We employed the WHO's excess mortality methodology using pre-pandemic data to estimate expected deaths during the pandemic period (March 2020 to August 2022). PARTICIPANTS: This study included ESRD patients from across Thailand, covered by the UCS. PRIMARY OUTCOME MEASURE: Excess deaths are the difference between predicted and reported deaths. RESULTS: Over a 30-month period of the pandemic, the total number of all-cause excess deaths among ESRD patients was 4966 (male 1284; female 3682). The excess death per 100 000 ESRD patients was 3601 (male 2012; female 4969). The relative excess death was 5.7% of expected deaths (95% CI 1.7%, 10.0%). The excess deaths were highly concentrated among patients aged 65 and older. CONCLUSION: ESRD patients are significantly more vulnerable to pandemic-related mortality than the general population. Health systems' capacity to contain the pandemic at varying virulence and maintain essential health services for ESRD patients might be related to the size of excess deaths at different periods. The observed excess deaths highlight the importance of established strategies to reduce all-cause mortality such as rapid vaccine rollout for ESRD patients and sustaining dialysis and other essential services for older patients and other high-risk groups.