While subclinical hypothyroidism (SCH) was reportedly associated with an increased risk of cardiovascular mortality, the relationship between SCH and clinical outcomes of patients undergoing percutaneous coronary intervention (PCI) is uncertain. The aim of this study was to assess the association of SCH and cardiovascular outcomes in patients undergoing PCI. We searched PubMed, Embase, Scopus, and CENTRAL databases from its inception until April 1, 2022 for studies comparing the outcomes between SCH and euthyroid patients undergoing PCI. Outcomes of interest include cardiovascular mortality, all-cause mortality, myocardial infarction (MI), major adverse cardiovascular and cerebrovascular events (MACCE), repeat revascularization and heart failure. Outcomes were pooled using the DerSimonian and Laird random-effects model and reported as risk ratios (RR) and 95% confidence intervals (CI). A total of 7 studies involving 1132 patients with SCH and 11,753 euthyroid patients were included in the analysis. Compared with euthyroid patients, patients with SCH had significantly higher risk of cardiovascular mortality (RR 2.16, 95% CI: 1.38-3.38, P < 0.001), all-cause mortality (RR 1.68, 95% CI: 1.23-2.29, P = 0.001) and repeat revascularization (RR 1.96, 95% CI: 1.08-3.58, P = 0.03). However, there were no differences between both groups in terms of incidence of MI (RR 1.81, 95% CI: 0.97-3.37, P = 0.06), MACCE (RR 2.24, 95% CI: 0.55-9.08, P = 0.26) and heart failure (RR 5.38, 95% CI: 0.28-102.35, P = 0.26). Our analysis suggests among patients undergoing PCI, SCH was associated with increased risk of cardiovascular mortality, all-cause mortality and repeat revascularization compared to euthyroid patients.