Pure steam systems are essential utilities in biopharmaceutical manufacturing, providing sterile steam for cleaning-in-place, sterilization-in-place, and equipment sterilization. However, validation data for pure steam remains limited compared with water systems. This study reports the comprehensive qualification and validation of a GMP-compliant pure steam system, including installation qualification, operational qualification, and performance qualification. Sampling was performed at five representative points of use over one year, twice weekly, to ensure robustness and reproducibility. Analytical testing covered physicochemical parameters (conductivity, total organic carbon, endotoxins), microbiological safety (viable counts, thermophiles, pathogens), and steam quality attributes (non-condensable gases, dryness fraction, superheat). Results consistently met pharmacopeial and regulatory requirements: conductivity < 1.0 µS/cm, total organic carbon < 100 ppb, endotoxins undetectable, and negligible microbial counts. Steam quality testing confirmed non-condensable gases < 2.0%, dryness fraction > 0.95, and controlled superheat. These outcomes align with European Pharmacopoeia, United States Pharmacopeia, EU GMP Annex 1, FDA guidance, and ISPE recommendations, demonstrating the reliability of pure steam systems for sterile manufacturing. The novelty of this work lies in presenting complete validation data for pure steam as an independent utility, contrasting with the limited case reports that address steam only within water-system validation. Additionally, the study highlights the importance of continuous monitoring and lifecycle management to maintain validated states, ensuring long-term compliance and operational robustness. By providing detailed evidence of system performance, this study supports industry efforts to strengthen quality assurance frameworks and to establish pure steam as a validated, reliable, and indispensable utility in biopharmaceutical production.