We conducted this study to explore the associations of weekend and weekday admission with the clinical events among heart failure (HF) patients with and without comorbid atrial fibrillation (AF). In this study, we recruited 57 919 HF patients without AF hospitalized on weekends and 57 919 HF patients without AF hospitalized on weekdays. There were 21407 and 21407 HF patients with AF hospitalized on weekends and weekdays, respectively. The outcomes of interest included all-cause mortality, cardiovascular (CV) death, and HF recurrence requiring admission. The Cox proportional hazard regression model was applied to estimate the hazard ratio. Variables found to be statistically significant in a univariable Cox proportional hazard regression model were further examined in a multivariable Cox proportional hazard regression model. The cumulative incidence curves were obtained by the Kaplan-Meier method and assessed by the log-rank test. HF patients with AF and hospitalized on weekends had the highest incidence rates of rehospitalization due to HF (233.8 per 1000 person-years) and CV death (23.9 per 1000 person-years) among four groups. The Kaplan-Meier method shows that HF patients with AF had the higher cumulative incidence of rehospitalization due to HF than the patients without AF. HF patients with AF and hospitalized on weekends are at highest risk of HF recurrence requiring hospitalization among these four groups. © The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.