Background: Taurine has been demonstrated to regulate and improve metabolic health. However, physiological and pathological differences among individuals with overweight or obesity may result in varied responses to taurine supplementation. This study aims to estimate the effects of long-term taurine supplementation on blood lipids, glycemia, and insulin sensitivity in adults with overweight or obesity through a systematic review and meta-analysis. Methods: The literature search was based on six databases (Web of Science, PubMed, Scopus, EMBASE, Cochrane, and SPORTDiscus) up to October 2024. Subgroup analyses were performed based on daily taurine intake dosage (<3 g or 3 g), overweight (BMI 25–29.9 kg/m²), and obesity (BMI ≥30 kg/m²). Results: The final number of studies that met the inclusion criteria was 9 RCTs. The overall analysis showed that taurine supplementation significantly decreased TG (WMD = −0.56 mg/dL, 95% CI: −0.92 to −0.2, p = 0.002, I² = 63%), TC (WMD = −0.71 mg/dL, 95% CI: −1.17 to −0.25, p = 0.002, I² = 73%), and fasting insulin (WMD = −2.15 µU/mL, 95% CI: −3.24 to −1.06, p = 0.0001, I² = 9%). In the subgroup analysis, long-term taurine intake led to BMI improvement in overweight adults (WMD = −1.14 kg/m², 95% CI: −1.81 to −0.47, p = 0.0008, I² = 0%). Meanwhile, improvements in HbA1c (WMD = −0.33%, 95% CI: −0.53 to −0.12, p = 0.002, I² = 16%) and HOMA-IR (WMD = −0.91, 95% CI: −1.74 to −0.08, p = 0.003, I² = 54%) were observed only in obese participants following taurine supplementation. Additionally, the long-term intake of 3 g of taurine significantly improved HbA1c (WMD = −0.37%, 95% CI: −0.61 to −0.13, p = 0.003, I² = 0%) and FPG levels (WMD = −7.14 mg/dL, 95% CI: −12.53 to −1.74, p = 0.003, I² = 70%) in overweight/obesity. Conclusions: Long-term taurine supplementation is particularly effective in improving glycemic control and insulin sensitivity in obesity. Furthermore, higher doses of taurine (3 g per day) demonstrate even greater improvements in glycemic control.