Abstract. Khambali, Denanda ET, Rusmiati, Nurmayanti D, Wardoyo IRE, Wardoyo S. 2025. Phytoremediation efficiency of Crinum asiaticum in enclosed spaces based on morphological traits and CO absorption dynamics. Biodiversitas 26: 6205-6211. Indoor air pollution, particularly carbon monoxide (CO), poses a serious health risk in poorly ventilated environments. This study evaluates the phytoremediation potency of Crinum asiaticum, a native ornamental species, in reducing indoor CO concentrations—an area with limited prior investigation. A quasi-experimental design was employed using a 1.2 m × 0.9 m × 0.7 m test chamber, into which CO gas sourced from a 110 cc petrol-powered motorcycle was introduced. Five groups were assessed: one control (no plants) and four treatment groups containing one to four C. asiaticum specimens. CO levels were measured before and 45 minutes after exposure using a calibrated gas detector. Descriptive analysis revealed a dose-dependent reduction in CO levels, with the T4 group achieving the greatest decrease of 28.40%. The T3 and T2 groups treatments reduced concentrations by 14.59% and 7.34%, respectively. The T1 group showed a modest reduction of 4.47%, indicating limited absorption capacity at minimal biomass. The Kruskal-Wallis test indicated significant differences among groups (p<0.001), confirming a positive correlation between plant quantity and CO absorption capacity. Although final CO concentrations remained above national indoor air quality standards, the findings underscore the potential of C. asiaticum as a natural biofilter. Its integration into indoor environments not only supports air remediation but also enhances biodiversity through the use of indigenous phytoremediator species. This study presents a novel, eco-friendly approach to mitigating indoor air pollution and advancing environmental health strategies.