Simon Sidamon-Eristavi was born in Tiflis, a scion of the Georgian noble family of Sidamoni, whose principal branch ran the duchy of Aragvi from 1578 to 1743. He was educated at the Cadets Corps and Mikhailovsky Artillery College. During World War I, he rose to the rank of colonel in the Russian army. When Georgia declared independence in 1918, Sidamon-Eristavi became one of the founding officers of the Georgian army. In 1921, he took part in the war against the invading Soviet Russian army as a divisional chief of staff. After the fall of the independent Georgian republic, he immigrated to the United States, where he obtained a degree in engineering from the Johns Hopkins University and worked, thereafter, as an engineer with several American companies. He was also involved with several Georgian emigre associations in the United States. In 1931, he was granted the United States citizenship. He died in New York City in 1964.