Background There has been resurgence in the use of bismuth quadruple therapy (proton pump inhibitor, bismuth, tetracycline and metronidazole) for treating Helicobacter pylori infection thanks to a three-in-one single-capsule formulation. Objective To evaluate the effectiveness and safety of the single-capsule bismuth quadruple therapy. Methods Data were collected in a multicentre, prospective registry of the clinical practice of gastroenterologists on the management of H. pylori infection, where patients were registered at the Asociación Española de Gastroenterología REDCap database on an electronic case report form until January 2020. Effectiveness by modified intention-to-treat and per-protocol as well as multivariable analysis were performed. Independent factors evaluated were: age, gender, indication, compliance, proton pump inhibitor dose and treatment line. Results Finally, 2100 patients were prescribed single-capsule bismuth quadruple therapy following the technical sheet (i.e. three capsules every 6 hours for 10 days). The majority of these patients were naive (64%), with an average age of 50 years, 64% women and 16% with peptic ulcer. An overall modified intention-to-treat effectiveness of 92% was achieved. Eradication was over 90% in first-line treatment (95% modified intention-to-treat, n = 1166), and this was maintained as a rescue therapy, both in second (89% modified intention-to-treat, n = 375) and subsequent lines of therapy (third to sixth line: 92% modified intention-to-treat, n = 236). Compliance was the factor most closely associated with treatment effectiveness. Adverse events were generally mild to moderate, and 3% of patients reported a severe adverse event, leading to discontinuation of treatment in 1.7% of cases. Conclusions Single-capsule bismuth quadruple therapy achieved H. pylori eradication in approximately 90% of patients in real-world clinical practice, both as a first-line and rescue treatment, with good compliance and a favourable safety profile.