In the junior division, Leonardi won the bronze medal with the Swiss relay team at the 1990 World Junior Championship in Les Saisies . Her greatest success is winning the bronze medal at the 2002 Winter Olympics as the final runner in the Swiss 4 × 5 km relay. Four years earlier she had finished fourth in the season after being overtaken by Italian Stefania Belmondo shortly before the finish line . Her best individual result in an Olympic race is tenth place over 30 kilometers in 2002. The best result at world championships is fifth place with the 1999 relay.
In 2003, 2005 and 2006 Leonardi won the Engadin Skimarathon , the most important cross-country race in Switzerland. In 2006 she won the Kangaroo Hoppet in Australia and 2011 the Transjurassienne in France. In 2008 and 2009 she won the Engadine Women's Run. In 2009, 2011 and 2012 she won the Gommerlauf .
In ski mountaineering, she won the Trofeo Mezzalama in 2005 together with Gloriana Pellissier and Christiane Nex . In 2006 she took first place at the World Championship in the Vertical Race .
successes
Victories in Worldloppet Cup races
Note: Before the 2015/16 season, the Worldloppet Cup was still called the Marathon Cup .
Switzerland
Lamoura
Falls Creek
2006: Natascia Leonardi Cortesi | 
2011: Mireia Miró Varela | 
2013: Laëtitia Roux | 
2015: Laura Orgué | 