The clan takes its name from the lands of Cranstoun in Midlothian, Scotland. They held lands in this region and played important roles in local affairs. The Cranstoun clan traces its origins to the medieval period and was associated with the noble family of Cranstoun, who held the title of Lord Cranstoun. They were prominent landowners and had connections with other powerful families and clans, including the Clan Douglas.
Throughout Scottish history, the Cranstouns were involved in regional politics and conflicts. They displayed loyalty to the Scottish crown and served as administrators, judges, and military commanders.