During the 2017 indoor season, she became the European champion at the European Indoor Championships with a jump of 4.85 m, setting a new height. In the 2017 summer season she set a world lead in the Rome Golden Gala with 4,85 and attempted for the first time to set a new world record. Two years after a disappointing performance at the 2015 World Championship where she missed the final, Stefanidi won the gold medal at the 2017 World Championships in Athletics in London, where she even broke her own Greek record – and set a new world lead for 2017 – by vaulting 4.91 m. Katerina completed her 2017 outdoor season undefeated (14 wins in a row) and winning the Diamond league final in Brussels.