It is unclear whether obese renal cell carcinoma (RCC) patients treated with targeted therapy have better survival. We conducted this meta-analysis to assess the prognostic significance of body mass index (BMI) in RCC patients treated with targeted therapy. We systematically searched PubMed, Embase, Cochrane Library, and Web of Science by November 17, 2021. We calculated effect outcomes using random-effects and fixed-effects models. Fifteen articles were identified. We found that RCC patients treated with targeted therapy with BMI over 25 obtained better overall survival (OS) (hazard ratio [HR] = 0.69, 95% confidence interval [CI] = 0.58-0.82, I2 = 75.5%, p < 0.001) and progression-free survival (PFS) (HR = 0.71, 95%CI = 0.55-0.92, I2 = 69.7%, p = 0.006) than patients with BMI below 25. Obese (BMI over 30) patients had remarkably better OS (HR = 0.77, 95%CI = 0.70-0.85, I2 = 0.0%, p = 0.439) and PFS (HR = 0.86, 95%CI = 0.77-0.97, I2 = 0.0%, p = 0.934) than patients with BMI below 25. Overweight (BMI over 25 but below 30) patients also had better OS (HR = 0.86, 95%CI = 0.79-0.93, I2 = 17.7%, p = 0.295) and PFS (HR = 0.82, 95%CI = 0.74-0.90, I2 = 0.0%, p = 0.904) than patients with BMI below 25. When using BMI as continuous variable, patients with high BMI also obtained significantly better OS (HR = 0.92, 95%CI = 0.88-0.96, I2 = 0.0%, p = 0.806). Therefore, higher BMI was associated with greater OS and PFS in RCC patients treated with targeted therapy.