The present invention describes a rapid, eco-friendly and room temperature based method of dyeing synthetic and natural fibers, yarns and fabrics for textile and biomedical applications. Further, the invention also discloses method of dyeing of hair for cosmetic purposes. Plasmonic nanoparticle synthesized using plant extract as reducing agent is used as dye herein. Modification in shape and size of the nanoparticles lead to different hues of colour.