Background: Ureteropelvic junction obstruction (UPJO) represents a common congenital anomaly in infants and young children. While minimally invasive approaches, including laparoscopic pyeloplasty (LP) and robot-assisted laparoscopic pyeloplasty (RALP), have gained acceptance, comparative outcomes in children younger than 3 years have still not been well-established. This study aimed to evaluate the safety and efficacy of RALP versus LP in infants and children younger than 3 years or weighing < 15 kg. Methods: A systematic literature search of PubMed, Web of Science, and Embase was conducted through May 2025. Five retrospective cohort studies comprising 272 patients met inclusion criteria (age younger than 3 years or weighing < 15 kg). Meta-analysis was performed using random-effects models. Results: Hospital stay was significantly shorter in the RALP group compared with LP (mean difference = −1.69 days; 95% CI: −2.71 to −0.67). No statistically significant differences were observed in operative time, complication rates, or success rates between approaches. Conclusions: RALP is associated with significantly reduced hospitalization time compared with LP in infants and young children, while maintaining comparable safety and efficacy profiles. These findings support RALP as a valuable minimally invasive option in this challenging patient population, though larger prospective studies are warranted.