In 2013, Steenbergen competed at the 2013 European Youth Summer Olympic Festival taking 2 silver medals in (50 m freestyle and 100 m freestyle). The swimming part of the Games were open to junior only. Steenbergen went on to represent the Netherlands at the 2015 World Aquatics Championships, competing in two relay events.
She did not swim in the final, but still received a medal.
She won the gold medal in the 100 m freestyle at the 2015 European Games. In June 2015, 15-year-old Steenbergen competed at the inaugural 2015 European Games in Baku, she won gold in 100 m freestyle ahead of Russia"s Arina Openysheva clocking in at 53.97 son Steenbergen also won five silver medals (in the 50 m freestyle, 200 m freestyle, 4×200 m freestyle, 4×100 m medley, and 4×100 m freestyle). She won a silver medal on the first day of competition in the women"s 4×100m freestyle relay, swimming the second leg in the heats and the third leg in the final. She won another silver medal as part of the mixed 4×100m freestyle, swimming the third leg in the heats. At the 2015 European Short Course Championships in December 2015, Steenbergen won her first international championship medal at the senior level in an individual event. She won the bronze medal in the 100-meter individual medley in 59.00 seconds, finishing behind Katinka Hosszú, who broke the world record, and Siobhan-Marie O"Connor.
