The textile industry is one of the most water-intensive sectors, primarily attributed to the substantial amount of water required for dyeing. During dyeing, wastewater containing synthetic dyes and auxiliary chemicals is produced, underscoring the need for more sustainable dyeing methods to address environmental concerns such as the release of pollutants. Supercritical carbon dioxide (scCO2) dyeing is an attractive sustainable method, as it is zero-water and zero-effluent. Coupled with an interest in utilizing natural dyes as renewable sources of color for textile coloration, this study investigated the feasibility of applying anthraquinone dyes from the madder plant (Rubia tinctorum L) including alizarin (an aglycone), and ruberythric acid/RA and lucidin primeveroside/LP (glycosides) using scCO2. Thus, the dyes (0.5%, 1% owf) were applied to polyester/PET (including recycled PET), nylon, and/or cellulose acetate at 120C, 34.45 MPa for 60 min, and the uptake of the dyes on the fibers were compared using water. Additionally, the uptake of the dyes was compared to a commercial synthetic dye known to display excellent uptake on PET using scCO2, C.I. Disperse Yellow 54/DY54. Furthermore, the light, wash, and crock fastness of dyed samples were evaluated. Alizarin exhibited affinity toward all fibers, with uptake ≥65%, notably the greatest for recycled PET (95.7±4.3%). In contrast, RA/LP exhibited low uptake (27.1±2.7%) on PET due to their hydrophilicity and poor affinity for hydrophobic fibers. The uptake of alizarin on the fibers was slightly greater using scCO2 compared to water, and the color of dyed samples resembled that of fibers dyed with DY54. Regarding fastness, PET fibers dyed using scCO2 displayed the best properties across the board. Taken together, these findings underscore the potential of using scCO2 to achieve sufficient uptake of alizarin on hydrophobic fibers without the need for water or auxiliary chemicals all while achieving good fastness properties.