Gregorio won the 2009 Junior European Championship in Odense. A year later she became Junior Italian champion. She joined the national team for the 2013 European Championships in Zagreb. She was eliminated in the first round by Germany's Alexandra Bujdoso. In the team event, Italy defeated France, but ceded against Russia in the semi-finals. They edged out Poland in the small final to take the bronze medal, Gregorio's first medal in a senior international event.