© 2020 by the authors. Licensee MDPI, Basel, Switzerland. Background: Clinical safety is a crucial component of healthcare quality, focused on identifying and avoiding the risks to which patients are exposed. Among the adverse events that occur in a hospital environment, falls have a large impact (1.9–10% of annual income in acute care hospitals); they can cause pain, damage, costs, and mistrust in the health system. Our objective was to assess the effect of an educational intervention aimed at hospital nurses (systematic assessment of the risk of falls) in reducing the incidence of falls. Methods: this was a quasi-experimental study based on a sample of 581 patients in a third level hospital (Comunitat Valenciana, Spain). An educational program was given to the intervention group (n = 303), and a control group was included for comparison (n = 278). In the intervention group, the nurses participated in a training activity on the systematized assessment of the risk of falls. Analysis was undertaken using the Bayesian logistic regression model. Results: a total of 581 patients were studied (50.6% male, 49.4% female), with an average age of 68.3 (DT = 9) years. The overall incidence of falls was 1.2% (0.3% in the intervention group and 2.2% in the control group). Most of the falls occurred in people ≥65 years old (85.7%). The intervention group had a lower probability of falling than the control group (OR: 0.127; IC95%: 0.013–0.821). Neither the length of hospital stay, nor the age of the participants, had any relevant effect. Conclusions: the systematic assessment of the risk of a patient falling during hospital processes is an effective intervention to reduce the incidence of falls.