Background: The lack of well-established operational definitions is a major limitation of Helicobacter pylori eradication studies that use secondary databases. We aimed to develop and validate operational definitions related to H. pylori eradication therapy. Methods: Operational definitions were developed by analyzing a nationwide H. pylori eradication registry and validated using real-world data from hospital medical records. The primary endpoint was the sensitivity of the operational definitions in identifying individuals who received H. pylori eradication therapy. The secondary endpoint was the sensitivity and specificity of the operational definition in identifying successful H. pylori eradication therapy. Results: H. pylori eradication therapy was defined as a prescription for one of the following combinations: 1) proton pump inhibitor (PPI) + amoxicillin + clarithromycin, 2) PPI + amoxicillin + metronidazole, 3) PPI + metronidazole + tetracycline, 4) PPI + amoxicillin + levofloxacin, 5) PPI + amoxicillin + moxifloxacin, or 6) PPI + amoxicillin + rifabutin. In the validation set, the sensitivity of the operational definition for identifying individuals who received H. pylori eradication therapy was 99.7% and 99.8% for the first- and second-line therapies, respectively. Operational definition to determine success or failure of the H. pylori eradication therapy was developed based on a confirmatory test and the prescription of rescue therapy. The sensitivity and specificity of the operational definition for predicting successful eradication were 97.6% and 91.4%, respectively, in first-line therapy and 98.6% and 54.8%, respectively, in second-line therapy. Conclusion We developed and validated operational definitions related to H. pylori eradication therapy. These definitions will help researchers perform various H. pylori eradication-related studies using secondary databases.