An ankle-foot orthosis includes a plantar flexion limiting device that limits the plantar flexion of the foot and which is configured to provide support for a user's foot drop. The ankle-foot orthosis includes a lower leg shell including a foot support and a lower leg support, and is configured to position and/or fix a user's heel in the lower leg support. The plantar flexion motion of the foot is limited by the complementary action of elastic and non-elastic portions of the plantar flexion limiting device. The plantar flexion limiting device further leads to a dynamic return of the foot to an angle substantially equal to the angle value α2.