The dye-removal potential of a common environmental isolate Trichoderma asperellum on four triphenylmethane dyes was studied via biosorption experiments using free-cells and alginate-immobilized forms. T. asperellum demonstrated potential to remove TPM dyes, with higher efficiency when alginate-immobilized forms were used compared to free-cells. Amount of crystal violet (CV), methyl violet (MV), cotton blue (CB), and malachite green (MG) adsorbed by immobilized forms were 60.64, 50.29, 49.91, and 16.61 mg g−1 compared to 12.97, 12.54, 14.34, and 11.44 mg g−1 by free-cells, respectively. Enhanced dye removals by alginate-immobilized T. asperellum were attributed to the carboxyl and hydroxyl functional groups present on the surface of alginate. For free-cells, their surface comprises amine and alkane groups which were less effective in binding dyes. This study is the first to report the dye-removal potential of T. asperellum for triphenylmethane dyes, and we recommend immobilized forms as suitable for application.