Muir finished fourth in the 1500m and sixth in the 5000m at the 2017 World Championships in London. Following the championships, she announced that she would miss the 2018 Commonwealth Games in April in order to focus on her veterinary medicine exams. She did compete in March 2018 at the World Indoor Championships in Birmingham, where she won a bronze medal in the 3000m, followed by a silver medal in the 1500m two days later. In August, she won the 1500 metres title at the 2018 European Championships in Berlin, the first British woman ever to win the European 1500m title. She followed this breakthrough by winning her second Diamond League title over 1500 metres, her second, but her first since the move to a championship format.