Abstract Background miR-223-3p has been demonstrated as a Pseudomonas aeruginosa colonization-related miRNA in bronchiectasis (BE), but its clinical value in BE has not been revealed, which is of great significance for the clinical diagnosis and monitoring of BE. This study aimed to identify a reliable biomarker for screening BE and predicting patients’ outcomes. Methods The serum expression of miR-223-3p was compared between healthy individuals (n = 101) and BE patients (n = 133) and evaluated its potential in distinguishing BE patients. The severity of BE patients was estimated by BSI and FACED score, and the correlation of miR-223-3p with inflammation and severity of BE patients was evaluated by Pearson correlation analysis. BE patients were followed up for 3 years, and the predictive value of miR-223-3p in prognosis was assessed by logistic regression analysis. Results Significant upregulation of miR-223-3p was observed in BE patients, which significantly distinguished BE patients and showed positive correlations with C-reactive protein (CRP), procalcitonin (PCT), interleukin 6 (IL-6), and neutrophil-to-lymphocyte ratio (NLR) of BE patients. Additionally, miR-223-3p was also positively correlated with BSI and FACED scores, indicating its correlation with inflammation and severity of BE. BE patients with adverse prognoses showed a higher serum miR-223-3p level, which was identified as an adverse prognostic factor and discriminated patients with different prognoses. Conclusion Increasing serum miR-223-3p can be considered a biomarker for the onset, severity, and prognosis of BE.