The ankle foot orthosis has a foot section securable externally to a footwear worn by a user, a leg section having a leg engagement portion extending in front of the user's lower leg and being securable against a shin area of the user's lower leg, and two arm portions extending downwardly from the leg engagement portion, on opposite sides of the user's lower leg, and a hinge section having two hinge members disposed on opposite sides of the user's ankle, each hinge member having two ends being elastically stretchable away from one another, with a first one of the ends being secured to a corresponding one of the leg arm portions, and a second one of the two ends being secured to the foot section, with a spacing between the hinge members and the arm portions forming a foot engagement path allowing the user to respectively engage or disengage his foot from the footwear across the spacing.