In November 2001 Løseth competed in her first FIS races , appearances in the European Cup followed from November 2002. She celebrated her first successes in 2003 when she won the silver medal in giant slalom at the Junior World Championships and the gold medal in slalom at the European Youth Olympic Winter Festival in Bled . On December 12, 2004 it was used for the first time in the World Cup at the slalom in Altenmarkt-Zauchensee . She achieved her first World Cup points in January 2006 with place 27 at the slalom in Zagreb .
Over the years Løseth was unable to establish himself in the World Cup. In most races she did not qualify for the second run. Her best results are two 20th places, which she achieved in the 2008/09 season at the slaloms at Semmering and Garmisch-Partenkirchen . She was more successful in the European Cup, where she celebrated her first victory in the giant slalom in Trysil on November 26, 2008 and finished second in the discipline classification at the end of the season. In the 2009/10 season she won the giant slalom classification with her second victory in Crans-Montana and another three podium places. At Norwegian championships , she won a total of five titles from 2005 to 2008.
Lene Løseth started at the 2007 World Championships in Åre . She was 23rd in the slalom and 38th in the giant slalom. At the 2009 World Championships in Val-d'Isère , she reached 19th place in the giant slalom. After missing World Cup points in the 2010/2011 season, Løseth announced her retirement from ski racing in February 2011.