Hyaluronic acid (HA) or hyaluronan has been a very important biopolymer for human health since it was first isolated from animal sources. This straight-chain biopolymer, consisting of β-D-glucuronic acid and N-acetyl-glucosamine disaccharide units, can be extracted from animal sources as well as produced by the natural producers Group A and Group C Streptococcus species. Besides, HA can be produced using engineered strains that are GRAS listed. HA, which is highly bioavailable due to its highly water binding capacity, viscoelasticity, and high molecular weight, is generally used in ophthalmology and eye surgery, orthopedics, aesthetic surgery, skin regeneration, detection and treatment of cancer cells, drug delivery systems, and the cosmetics industry. This chapter provides a comprehensive overview of hyaluronic acid, highlighting its structural features, biological functions and major applications, with a particular focus on microbial production strategies. Streptococcal biosynthesis, related metabolic pathways, fermentation parameters, and downstream processing techniques are discussed in this chapter. Recent advances in genetic and metabolic engineering related to HA production are also presented.