Currently, the synthesis of nanostructured inorganic materials with tunable morphology is still a great challenge. In this study, almond skin extract was employed for the biogenic synthesis of selenium nanoparticles with tunable morphologies such as rods and brooms. The effects of various synthesis parameters on morphologies were investigated using UV-Visible spectroscopy and scanning electron microscopy (SEM) which indicated that selenium brooms (SeBrs) were best synthesized using almond skin extract and optimized conditions of SeO2, ascorbic acid, pH, incubation temperature and time. Based on these results, the mechanism of SeBrs synthesis is proposed as having involved four stages such as nucleation, self-assembly, Ostwald ripening, and decomposition. Further, the test of antibacterial activity together with minimum inhibitory concentrations and minimum bactericidal concentrations indicated the selective, specific and good activity against B. subtilis. In addition, in situ coating of SeBrs on cotton fabric and its investigation by SEM demonstrated successful coating. Evident from plate-based assay and study of growth kinetics, coated fabric exhibited excellent anti-B. subtilis activity which demonstrated that biogenic SeBrs can be employed to coat cotton fabrics that can be used in operation theatres to reduce the episodes of Bacillus related Bacteraemia. (C) 2020 Elsevier Inc. All rights reserved.