Wierer has won her first Biathlon World Championships medal placing third in the Women's relay together with Nicole Gontier, Michela Ponza and Karin Oberhofer at the Biathlon World Championships 2013 in Nové Město na Moravě, which was the first ever medal for Italian women at the Biathlon World Championships. At the 2019 Championships in Östersund she won the gold medal in the 12.5 km Mass Start, also a first for Italian women in Biathlon. She has currently won 10 medals in total, including 3 Golds, 4 Silvers and 3 Bronzes.