Arcanjo had significantly improved when she returned to action in 2012, setting a series of personal bests on the Brazilian circuit. She cleared eighteen metres for the first time at the 2012 Ibero-American Championships in Athletics, where she won the shot put with a personal best of 18.84 metres. After winning her first Brazilian title, she was selected for the Brazilian team for the 2012 London Olympics. Her throw of 19.02 metres in the Olympic final was enough for seventh place. She ended her season with a win at the 2012 South American Under-23 Championships in Athletics.