The Mon language (Mon: ဘာသာ မန်; Burmese: မွန်ဘာသာ) is an Austroasiatic language spoken by the Mon, who live in Burma (Myanmar) and Thailand. Mon, like the related language Cambodian—but unlike most languages in Mainland Southeast Asia—is not tonal. Mon is spoken by more than a million people today. In recent years, usage of Mon has declined rapidly, especially among the younger generation. Many ethnic Mon are monolingual in Burmese. In Burma, the majority of speakers live in Mon State, followed by Tanintharyi Division and Kayin State.

The Mon script is derived from Indian Brahmi script and is the source of the Burmese script.

Mon is an important language in Burmese history. Up until the 12th century AD, it was the lingua franca of the Irrawaddy valley—not only in the Mon kingdoms of the lower Irrawaddy valley but also of upriver Burman kingdom of Pagan (Bagan). Mon, especially written Mon, continued to be the primary language even after the fall of the Mon kingdom of Thaton to Pagan in 1057. Pagan king Kyansittha (r. 1084–1113) admired the Mon culture, and the Mon language was patronized. The Mon script was the source of the Burmese script created during his reign. Kyanzittha left many inscriptions in Mon. During this period, the Myazedi inscription, which contains identical inscriptions of a story in Pali, Pyu, Mon, and Burmese on the four sides was carved. However, after Kyansittha's death, usage of the Mon language declined among the Burmans. Old Burmese began to replace Mon and Pyu as lingua franca.