IBU Cup
Whilst competing for Belgium, Rösch initially trained with Alexander Os and Lars Berger, who had similarly been dropped by the Norwegian Biathlon Association, in a training group they humorously nicknamed the "Feskslog" - Norwegian for "fish waste". He later switched to training with the Swiss biathlon squad. He made his debut for Belgium at an IBU Cup meeting in Martell, Italy in March 2014, taking two top 20 finishes in the sprint and pursuit there. These performances earned him a wild card for the 2014-15 World Cup season. After switching countries, in August 2014 he became the first Belgian biathlete to win a global title when he took the gold medal in the pursuit at the Summer Biathlon World Championships in Tyumen, Russia, having already taken a silver in the sprint the previous day. Rösch also led the first Belgian World Cup relay team. In December 2016, he finished sixth in the pursuit at the Pokljuka World Cup meeting - his first top ten World Cup finish in solo competition since 2009: Rösch subsequently said that this result was "a bigger success than the Olympic gold medal. There was a lot more in it after all the setbacks". In a tearful interview by the finish line, he dedicated the result to his late former coach, Klaus Siebert. He also became the first Belgian to take a podium in the top two tiers of biathlon competition when he finished second in an IBU Cup race.