Cystathionine-β-synthase plays a key role in the metabolism of sulfur-containing amino acids, particularly in the transsulfuration pathway that converts homocysteine to cystathionine, a precursor for cysteine and glutathione. This enzymatic activity is critical for maintaining cellular redox balance due to glutathione’s role as a major antioxidant. The enzyme is also a target for therapeutic intervention in conditions involving elevated homocysteine levels, such as hyperhomocysteinemia, which is linked to cardiovascular disease, stroke, and cognitive disorders. Modulation of its activity, either through cofactor supplementation (like vitamin B6) or pharmacological agents, is explored in managing metabolic disorders including homocystinuria. Additionally, research into CBS inhibitors is ongoing for potential use in cancer therapy and inflammatory diseases, where hydrogen sulfide—produced in part by this enzyme—acts as a signaling molecule with both protective and pathological effects depending on concentration and context.