Background: The placement of an electrode catheter into the coronary sinus (CS) is critical for electrophysiologic studies. While central venous approaches (e.g., internal jugular or subclavian) are well-documented, peripheral venous approaches like the cubital vein are not. This study aimed to evaluate the feasibility and safety of CS catheter placement via the right cubital vein during atrial fibrillation (AF) ablation. Methods: Of 1363 consecutive patients who underwent first-time AF ablation at our institution between January 2019 and December 2021, we investigated 1274 who had at least one attempt at right cubital vein puncture for CS catheter placement. We evaluated the success rate, causes of placement failures, and complications associated with the cubital vein approach. Results: The CS catheters were successfully placed via the right cubital vein in 1214 (95.3%) patients, while 60 (4.7%) had unsuccessful placements. While older patients were more likely to experience unsuccessful placements, there were no significant differences in other baseline characteristics. Unsuccessful placements were attributed to failure in venipuncture or 7 Fr sheath insertion (n = 49) and failure to advance the CS catheter through the vein (n = 11). No major complications were reported. Conclusions: CS catheter placement via the right cubital vein was generally safe with few adverse events and a success rate of approximately 95%. This approach offers a practical alternative for placing CS catheters, particularly in patients with adequate vein development.