This study aimed to analyze the incidence, clinical characteristics, and risk factors of moxifloxacin‐related arrhythmias and electrocardiographic alterations in hospitalized patients using real‐world data. Concurrently, a nomogram was established and validated to provide a practical tool for prediction. Retrospective automatic monitoring of inpatients using moxifloxacin was performed in a Chinese hospital from January 1, 2017, to December 31, 2021, to obtain the incidence of drug‐induced arrhythmias and electrocardiographic alterations. Propensity score matching was conducted to balance confounders and analyze clinical characteristics. Based on the risk and protective factors identified through logistic regression analysis, a prediction nomogram was developed and internally validated using the Bootstrap method. Arrhythmias and electrocardiographic alterations occurred in 265 of 21,711 cases taking moxifloxacin, with an incidence of 1.2%. Independent risk factors included medication duration (odds ratio [OR] 1.211, 95% confidence interval [CI] 1.156–1.270), concomitant use of meropenem (OR 4.977, 95% CI 2.568–9.644), aspartate aminotransferase >40 U/L (OR 3.728, 95% CI 1.800–7.721), glucose >6.1 mmol/L (OR 2.377, 95% CI 1.531–3.690), and abnormally elevated level of amino‐terminal brain natriuretic peptide precursor (OR 2.908, 95% CI 1.640–5.156). Concomitant use of cardioprotective drugs (OR 0.430, 95% CI 0.220–0.841) was a protective factor. The nomogram showed good differentiation and calibration, with enhanced clinical benefit. The incidence of moxifloxacin‐related arrhythmias and electrocardiographic alterations is in the range of common. The nomogram proves valuable in predicting the risk in the moxifloxacin‐administered population, offering significant clinical applications.