In 2018, Stefanidi increased her collection of medals, taking the third place (4.80 m.) at the World Indoor Championships in Birmingham, and the first place (4.85 m) at the European Championships in Berlin. She won the 2018 Diamond League series (4.87 m) for a third consecutive year and completed the season with a second place (4.85 m) behind Anzhelika Sidorova, representing Europe at the Continental Cup.