Water pollution by toxic dyes such as Eriochrome Black T (EBT) is an increasing environmental issue, and the use of biosorbents represents a sustainable alternative for their treatment. In this study, the ability of Aspergillus niger QH27 fungal biomass in removing EBT under various experimental conditions was investigated. The main objective was to evaluate biosorption efficiency and determine the optimal conditions for dye removal. The methodology consisted of performing experiments by varying pH (5, 7 and 9) and agitation speed (100, 150 and 200 rpm), and analysing dye removal efficiency and adsorption capacity. Results showed that EBT removal was most effective at low pH values and higher agitation speeds. At a pH of 5 and agitation of 200 rpm, the maximum removal efficiency (99.17 %) and adsorption capacity (1.24 mg/g) were achieved. Fourier transform infrared spectroscopy (FTIR) analyses were carried out to examine the changes in functional groups of fungal biomass before and after EBT biosorption. FTIR results suggested the active involvement of these groups in the dye removal process. In conclusion, Aspergillus niger QH27 biomass proved to be an efficient biosorbent for the removal of EBT dye in aqueous solutions. This study provides valuable information for the development of sustainable and low-cost strategies in treating wastewater contaminated with dyes and expands the knowledge of dye biosorption using fungal biomass.