He finished the 2018–19 Four Hills Tournament in 22nd place overall. The best individual result of his career so far was achieved on the weekend after the 4-Hills Tournament with fifth place in Val di Fiemme, Italy. On 19 January 2019, Siegel achieved his first World Cup victory together with Karl Geiger, Markus Eisenbichler and Stephan Leyhe in the team competition in Zakopane. In the second round, however, he crashed hard after landing and suffered a cruciate ligament tear, which meant the season's out. Also the following season missed seals due to this injury, in which also the inner ligament, the meniscus and even more in the right knee ripped. In his comeback in August 2020 at the Grand Prix in Wisła, Siegel reached the points.