From December 2004 Benna was used in the European Cup and one month later she could book her first podium. He made his debut in the Freestyle World Cup on February 18, 2005 in Sauze d'Oulx , and won his first World Cup points on December 14 of the same year with 18th place in Tignes . At the Junior World Championships 2006 in Krasnoye Ozero, Benna won the silver medal in the Mughal competition. In the World Cup, he was initially able to establish himself in the midfield and in March 2007, finishing fourth in Voss, barely missed a podium. This was a long time coming until December 18, 2008, when he came third in Méribel's dual moguls competition.
Benna qualified for the 2010 Winter Olympics , but only reached 30th place in the Cypress Mountain Olympic competition . Due to injury, he had to skip part of the 2010/11 season . At the beginning of the 2011/12 World Cup season, he achieved two podium places in a row. After that he could no longer build on these achievements; He was only sporadically placed in the top 10. In the first World Cup competition of the 2014/15 season , Benna was on the podium again. Surprisingly, he won the gold medal in the Moguls competition at the 2015 World Championships on the Kreischberg , ahead of the favorite Canadian Mikaël Kingsbury . On March 15, 2015, he achieved his first World Cup victory in Megève .
Although Benna won another dual moguls competition on February 6, 2016 in Deer Valley , his other performances in the 2015/16 World Cup season were very inconsistent. In the winter of 2016/17 , three eighth places remained his best results.