Background: Calcium is critical in coagulation and platelet activation, making it a key factor in managing hemostasis during cardiac catheterization. Pediatric patients undergoing this procedure face unique physiological challenges, with a heightened risk of thrombotic and bleeding complications. This study evaluates the association between calcium levels and procedural outcomes in children undergoing cardiac catheterization. Methods: A prospective observational study was conducted at Ayub Teaching Hospital from January 2023 to January 2024. One hundred pediatric patients undergoing diagnostic or interventional cardiac catheterization were included. Baseline and post-procedural calcium levels, coagulation profiles, and demographic data were collected. Procedural parameters anticoagulant use, contrast volume, and fluoroscopy time were also recorded. Outcomes, including thrombotic and bleeding events, were analyzed, with statistical significance at p<0.05. Results: The mean age of participants was 8.5 ± 4.2 years, with a male-to-female ratio of 60:40. Baseline calcium levels (mean: 9.2 ± 0.8 mg/dL) and ionized calcium levels (mean: 4.5 ± 0.2 mg/dL) were within normal ranges. Thrombosis occurred in 5% of patients, predominantly at access sites, while bleeding was observed in 10%, with 8% minor and 2% significant cases. Post-procedural calcium levels remained stable at 9.0 ± 0.6 mg/dL. Significant associations were found between calcium levels, thrombotic (p=0.027), and bleeding events (p=0.024). Hospital stays averaged 3 ± 1.2 days, with no mortality reported. Conclusion: Stable calcium levels are critical for minimizing thrombotic and bleeding complications during pediatric cardiac catheterization. These findings underscore the importance of calcium monitoring and management in improving procedural safety and outcomes. Further multicenter studies are recommended to validate these results and explore optimized management strategies.