Hasselborg won her first Grand Slam in the lone women's Elite 10 in 2018, going undefeated through the tournament and defeating Silvana Tirinzoni in the final. A few weeks later, she won her second career Stockholm Ladies Cup. Then, at the 2018 Masters, Hasselborg won her second straight slam, defeating Rachel Homan in the final. The following month, Hasselborg and her team took home the gold medal at the 2018 European Curling Championships, her first gold medal at the Euros, defeating Swtizerland's Tirinzoni rink in the final. Hasselborg lost the world final once again at the 2019 World Women's Curling Championship, this time losing to Tirinzoni. She was however victorious at the 2019 World Mixed Doubles Curling Championship with partner Oskar Eriksson. The team secured the number one spot in the playoffs en route to defeating the Canadian pair of Jocelyn Peterman and Brett Gallant in the final.