Background: Skin diseases are highly prevalent worldwide. Although plant-derived medicinal materials continue to be used among Mongolians for the traditional and household management of dermatological conditions, studies that systematically quantify their frequency of use, informant consensus, and cultural significance remain limited. Aim: To determine the traditional knowledge, patterns of use, and cultural significance of plant-derived medicinal materials used for dermatological conditions among residents of Ulaanbaatar using quantitative ethnobotanical indices. Materials and Methods: Information was collected on the diversity of plant species used for dermatological conditions, modes and frequency of use, perceived effectiveness, adverse effects, and methods of preparation and processing. The collected data were evaluated using quantitative ethnobotanical indices, including the Use Value (UV), Relative Frequency of Citation (RFC), Informant Consensus Factor (ICF), Fidelity Level (FL), Relative Popularity Level (RPL), Rank Order Priority (ROP), Cultural Importance Index (CII), Jaccard Index (JI), and Shannon–Wiener Diversity Index (SDI). Statistical analyses were performed using Microsoft Excel 2016. The study was conducted with the approval of the Research Ethics Review Committee of the Mongolian National University of Medical Sciences (Approval Protocol No. 25-06/03-03 and Ethical Opinion Protocol No. 26/03-B02). Result: A total of 73 plant species belonging to 36 families were documented, with species from the Asteraceae, Rosaceae, Apiaceae, and Liliaceae families being predominant. Regarding modes of use, 29.6% of the remedies were prepared as infusions or decoctions and applied as washes or topical applications, 18.9% involved the direct application of plant juice, and 18.1% were applied as mashed plant material or poultices. Aloe barbadensis showed the highest ethnobotanical importance, with UV= 0.19, RFC=0.128, CII=0.19, RPL=1.00, and ROP=100. Nugaraa altan tovch, Gobi thyme, yashilduu sea buckthorn, and greater plantain were also highly ranked. The Informant Consensus Factor was highest for thermal burns (ICF=0.82), followed by open wounds (ICF=0.77) and pustular acne (ICF=0.76). Eighteen species overlapped with the 126 medicinal materials recorded in traditional medicinal prescriptions, yielding a Jaccard Index of JI=10%. The Shannon–Wiener diversity index was H′=3.4184, with an evenness value of E=0.7967. Among the informants, 40.8% reported a reduction in symptoms, while 61.9% reported no adverse effects associated with the use of plant-derived medicinal materials. Conclusion 1. Among residents of Ulaanbaatar, information was documented on the use of 73 plant species belonging to 36 families for skin diseases. Knowledge of these plants was transmitted mainly within families, and topical methods of use, including washing with herbal infusions, rinsing, and direct application of expressed plant juice, were predominant. 2. According to the quantitative ethnobotanical indices, Aloe vera showed the highest values for use, citation frequency, and cultural importance. Matricaria chamomilla L., Thymus gobicus Tschern., Hippophae rhamnoides L., and Plantago major L. also ranked highly. The highest Informant Consensus Factor (ICF) values were observed for thermal burns, open skin wounds, and acne vulgaris.