At the conclusion of a repositioning flight with no passengers on board, a cabin attendant was seriously injured when she was struck by an unsecured galley cart during landing. Contrary to company training, guidance, and checklists, the cabin attendant was standing in the forward cabin, and the galley cart was left unsecured in the aft galley prior to touchdown. During landing and deceleration, the cart travelled the length of the cabin and collided with the unseated cabin attendant. According to the cabin attendant, the cart that struck her was part of her area of responsibility, and examination of the galley cart wheel locks and the galley cart receptacle locks after the accident revealed they operated as designed, with no anomalies noted.