Background: Excessive daytime sleepiness (EDS) has a negative impact on quality of life, work productivity and potentially increasing the risk of work-related accidents. Due to their shift systems, firefighters are vulnerable to having EDS. However, there has been limited research on EDS among firefighters, particularly in Indonesia. Aims: To assess the prevalence of EDS among Indonesian firefighters and identify associated factors. Methods: A cross-sectional survey of firefighters working at a district level Firefighters Department in a district of West Java, Indonesia, was undertaken in October 2023. Firefighters were interviewed to assess factors related to EDS. Their sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) (‘poor sleep’ if PSQI score ≥6), and Epworth Sleepiness Scale (ESS) was used to assess the presence of EDS (if ESS score >9). Binary logistic regression was used to identify factors associated with EDS. Results: The overall respective mean (SD) scores of PSQI and ESS among firefighters were 5.02 (2.33) and 6.50 (3.48). Of 130 firefighters, 59 (45%) had poor sleep quality, and 35 (27%) experienced EDS. The EDS was statistically significantly correlated with poor sleep quality (aOR = 2.66; 95% CI 1.09–6.46) and undertaking shift working (aOR = 2.65; 95% CI 1.00–6.99). Conclusions: Firefighters had substantial EDS problems, correlated with poor sleep quality and shift working. Revisiting shift work policy and working practices, providing better facilities for taking a rest during working hours and early identification of poor sleep quality may reduce the prevalence of EDS among firefighters. © The Author(s) 2025. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved.