BackgroundHospital visits constitute a ‘window of opportunity’ for initiating smoking cessation attempts, and healthcare providers (HCPs) play an important role in supporting patients to stop smoking. Yet, the current practices of supporting smoking cessation in the hospital setting are largely unexplored. The aim of this study was to explore practices of smoking cessation support among hospital-based HCPs.MethodsHCPs working in a large hospital in the secondary care sector completed an online, cross-sectional survey, including sociodemographic and work-related factors as well as 21 questions assessing practices of smoking cessation support based on the “five As” framework. Descriptive statistics were computed, and predictors of HCPs giving patients advice to stop smoking were explored using logistic regression analysis.ResultsAll employees (N = 3998) in the hospital received a survey link; 1645 (41.1%) HCPs with daily patient contact completed the survey. Smoking cessation support in the hospital setting was limited with regard to assessment of smoking; providing information and advice; planning and referral for further support; and follow-up on smoking cessation attempts. Almost half (44.8%) of participating HCPs with daily patient contact never or rarely advise their patients to stop smoking. Physicians were more likely than nurses to advice patients to stop smoking, and HCPs in outpatient clinics were more likely to give advice than inpatient clinic HCPs.ConclusionSmoking cessation support is very limited in the hospital-based healthcare setting. This is problematic, as hospital visits can be windows of opportunity to help patients change their health behaviour. An intensified focus on the implementation of hospital-based smoking cessation support is needed.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12913-023-09657-4.