Aims: To examine the association between nursing unit safety culture, quality of care, missed care and nurse staffing levels, and inpatient falls using two data sources: incidence of falls and nurses' perceptions of fall frequency in their units. The study explores the association between the two sources of patient falls and identifies if nurses' perceptions of patient fall frequency reflect the actual patient falls recorded in the incident management system. Background: Inpatient falls are associated with severe complications that result in extended hospitalisation and increased financial consequences for patients and healthcare services. Design: A multi-source cross-sectional study guided by the STROBE guidelines. Methods: A purposive sample of 33 nursing units (619 nurses) from five hospitals completed an online survey from August to November 2021. The survey measured safety culture, quality of care, missed care, nurse staffing levels and nurses' perceptions of patient fall frequency. In addition, secondary data on falls from participating units between 2018 and 2021 were also collected. Generalised linear models were fitted to examine the association between study variables. Results: Nursing units with strong safety climate and working conditions and lower missed care were associated with lower rates of falls using both data sources. Nurses' perceptions of the frequency of falls in their units were reflective of the actual incidence rate of falls, but the association was not statistically significant. Conclusion: Nursing units with a strong safety climate and better collaborations between nurses and other professionals, including physicians and pharmacists, were associated with lower incidents of patient falls. Relevance to Clinical Practice: This study provided evidence for healthcare services and hospital managers to minimise patient falls. Patient or Public Contribution: Patients who had experienced a fall, which was reported in the incident management system, from the included units in the five hospitals were part of this study.