Mesoxalic acid (2-oxopropanedioic acid, C₃H₂O₅) and its reduced form, tartronic acid (2-hydroxypropanedioic acid, C₃H₄O₅), represent a unique class of dicarboxylic acids with significant and multifaceted pharmacological potential. Despite their structural simplicity, these three-carbon dicarboxylic acids serve as versatile scaffolds for drug development across multiple therapeutic domains. This comprehensive review systematically examines the chemical properties, synthesis pathways, natural occurrence, and ethnopharmacological background of mesoxalic acid and tartronic acid. We provide an in-depth analysis of their pharmacological activities, including antioxidant, anti-inflammatory, metabolic regulatory, antimicrobial, bone-sparing, and neuroprotective properties. The review covers mechanisms of action at molecular and cellular levels, with particular emphasis on: (1) the inhibition of HIV-1 reverse transcriptase translocation by 4-chlorophenylhydrazone of mesoxalic acid (CPHM), representing a novel mechanism distinct from approved nucleoside and non-nucleoside RT inhibitors; (2) the recently discovered inhibition of pathological calcium oxalate crystallization by tartronic acid for kidney stone prevention; (3) the modulation of α-ketoglutarate dehydrogenase complex activity and its implications for neuroprotection; and (4) the emerging role of glyoxylate-dicarboxylate metabolism in the human gut microbiome and its association with metabolic disorders. Clinical applications, toxicological profiles, and future research directions are critically evaluated. Based on analysis of peer-reviewed studies spanning over six decades, we conclude that mesoxalic acid and tartronic acid warrant further investigation as therapeutic agents, particularly in metabolic disorders, inflammatory conditions, bone metabolism disorders, neurodegenerative diseases, and as adjuvants in antiviral therapy.