Poly-γ-glutamic acid sodium salt (γ-PGA-Na) is a water-soluble, biodegradable, and non-toxic anionic polymer produced by microbial fermentation. It is composed of D- and L-glutamic acid units linked through γ-amide bonds, distinguishing it from the α-linked polyglutamic acid found in proteins. Its high molecular weight and polyanionic nature confer excellent water retention, film-forming, and chelating properties. Its primary applications are in the pharmaceutical, cosmetic, and food industries. In pharmaceuticals, it serves as a novel functional excipient, acting as a bioadhesive material, a drug carrier for sustained release, and a stabilizer. In cosmetics, it is a highly effective humectant and moisturizer, superior to hyaluronic acid in some aspects. In food, it is used as a thickener, stabilizer, and dietary fiber supplement. It is also explored in agriculture as a fertilizer synergist and in environmental applications for heavy metal adsorption. Due to its natural origin, biocompatibility, and versatile functionality, γ-PGA-Na is considered a valuable multifunctional biopolymer with growing commercial interest across several sectors.