Background: Retrograde Intrarenal Surgery (RIRS) has emerged as a minimally invasive alternative for the management of renal calculi, especially in cases where extracorporeal shock wave lithotripsy (ESWL) or percutaneous nephrolithotomy (PCNL) are less suitable. It offers the advantages of reduced morbidity, shorter hospital stay, and faster recovery. However, its efficacy can vary based on stone size, location, and patient-related factors. Objectives: To evaluate the efficacy, safety, and outcomes of RIRS for renal stones in a single tertiary care centre, and to assess the stone-free rate (SFR), complication rate, and need for auxiliary procedures. Methodology: A prospective observational study was conducted over 12 months (September 2023 to September 2024) at the Pakistan Kidney Centre, involving patients who underwent RIRS for renal stones. Inclusion criteria were patients aged 18–70 years with renal calculi ≤20 mm. Patient demographics, stone characteristics, operative time, intraoperative findings, post-operative complications, and stone-free status at 4 weeks were recorded. Follow-up included imaging to confirm SFR. Descriptive statistics and relevant inferential tests were applied using SPSS version 28. Results: A total of 150 patients (mean age: 42.5 ± 10.9 years; 96 males, 54 females) underwent RIRS. The mean stone size was 13.8 ± 4.1 mm. The overall stone-free rate at 4 weeks was 87.3%. Operative time averaged 53 ± 13 minutes. Minor complications (Clavien-Dindo Grade I–II) occurred in 11.3% of cases, including transient hematuria and fever. No major complications or need for conversion to open surgery were observed. Auxiliary procedures were required in 5.3% of cases. Conclusion: RIRS is an effective and safe procedure for managing renal stones up to 20 mm, with high stone clearance rates and minimal morbidity. It should be considered a frontline treatment in appropriate candidates, particularly in centres with experienced endourologists and suitable facilities.