The invention is an ankle derotation and subtalar stabilization system that incorporates a pivoting adjustable-tension oblique tether strap that is anchored to both a forefoot component and leg component, and that is contiguous with pivoting adjustable-tension derotation strap that passes behind the leg and that is secured to a leg component. The system restrains oppositely directed rotation between the foot and the leg, and can actually after the normal biochemical relationship in a manner that produces foot rotation in a direction opposite to that which is normally coupled with leg rotation, without restriction of upward and downward foot movement. The primary application for the system is restraint of excessive subtalar joint inversion, leg external rotation, and anterolateral rotary displacement of the talus, but it can also be configured to restrain subtalar eversion and leg internal rotation through its incorporation into the structure of an ankle orthosis or shoe.