She is a two-time national champion in the women's 5000 metres. She represented Italy at the 2008 Summer Olympics, the 2012 Summer Olympics, and at the World Championships in Athletics in 2007 and 2009. Weissteiner was the runner-up at the European Cup 10000m in 2006 behind Elvan Abeylegesse. She won her first major continental medal at the 2007 European Athletics Indoor Championships. Her bronze medal performance with a run of 8:44.81 was a new Italian indoor record, marking an improvement of over twelve seconds for the distance.