Introduction: High quality and effective ventilation system operation plays a major role in maintaining indoor air quality in critical care unit (CCU). Aim of this study was to detect the role of antimicrobial-air-purifier in reducing the colony counts of microbes in air and high surface. Methods: This prospective study was conducted in CCU over a period of 18 months from November 2022 to May 2024 after approval from Hospital Ethics Committee. Microbial load was tested in CCU in the presence of and absence of purifier and air/high touch surface sampling was done by using settle-plate method on consecutive days in two phases (with/without purifier). Microorganism culture and identification was done using VITEK-2, and colony counting was performed using Omeliansky formula. Results: The comparison of microbial load in the CCUs between two phases revealed significant difference in the air and surface on days 1, 7, 14, 30, and 60 (p < 0.0001). Among gram-positive cocci (GPC), the most common isolate identified was coagulase-negative Staphylococcus species [35 (92.10%)], followed by Micrococcus luteus [5 (13.15%)] and Staphylococcus aureus [1 (2.63%)]. All GPC were resistant to methicillin and erythromycin while 1 (5%) strain was resistant to vancomycin, teicoplanin, and linezolid. Among gram-negative bacilli (GNB), the most common isolate was Acinetobacter species [8/23 (34.78%)], followed by P. species [5 (21.74%)]. About 19−23 (85−100%) GNB strains were resistant to third-generation cephalosporins and beta-lactam and beta-lactamase inhibitors. About 9−15 (42.3−67.64%) were resistant to tigecycline and carbapenems. Decreased bloodstream infections/catheter-associated urinary tract infections (CAUTI) rate of 3.49−2.92/3.97−1.95/1,000 patient-days was observed in CCU, while the device utilization ratio was same. Conclusion: Antimicrobial air purifier showed an effective role in decreasing the central line-associated blood stream infections and CAUTI rates in CCU.