Background: Rasagiline monotherapy is approved in early Parkinson’s disease (PD) for motor benefit. However, the efficacy and optimal rasagiline dosage in improving Unified Parkinson’s Disease Rating Scale (UPDRS) subscale scores between Japanese and Caucasian individuals remain uncertain. Aims: To investigate the efficacy of rasagiline monotherapy and evaluate differences between early PD patients in Eastern and Western countries. Methods: The study design involved the meta-analysis of randomized controlled trials identified using electronic databases. Results: The mean difference (MD) in total UPDRS scores indicated no significant difference between the 1 and 2 mg rasagiline (MD = −0.00, 95% confidence interval (CI) = −0.82 to 0.81). Compared with the placebo, the MD of UPDRS part I scores significantly improved in the 1 mg (MD = −0.33, 95% CI = −0.57 to −0.10) but not in the 2 mg. For UPDRS part II scores, the MD significantly improved in the 1 mg (MD = −0.87, 95% CI = −1.48 to −0.27) and 2 mg (MD = −0.98, 95% CI = −1.28 to −0.68). Regarding the UPDRS part III, the MD significantly improved in both (1 mg: MD = −2.41, 95% CI = −3.26 to −1.56; 2 mg: MD = −2.05, 95% CI = −2.64 to −1.46). The most commonly reported adverse events were headaches, back pain, and dizziness, with no statistical difference between the 1 mg rasagiline and placebo groups. Subgroup analysis revealed similar effects between Asian and Western participants. Conclusion: Rasagiline monotherapy at 1 mg per day is recommended for patients with early PD because of the benefits for motor, nonmotor functions, and safety.