Background: Although the treatment of sepsis has advanced during the past 20 years there is still a high incidence and high mortality, which make sepsis one of the leading public health problems. Adequate knowledge of sepsis and the sepsis guidelines is still the most important pillar for nurses because of the long time they spend with critically ill patients. Given their frontline role in patient care, nurses are pivotal in early sepsis recognition, timely intervention, and ensuring adherence to treatment protocols. Aim: This study aimed to investigate nursing students’ knowledge of sepsis and the symptoms of sepsis, and to compare the results of nursing students from several European universities (Croatia, Cyprus, Greece). Methods: A cross-sectional design was used, with a sample of 626 undergraduate nursing students from Croatian, Cypriot, and Greek universities from 2022 to 2023. Demographic features (gender, age, employment, year of study) and a questionnaire provided by Eitze et al. were utilized as instruments. Results: There was a statistically significant difference among the countries (F(2.625) = 4.254, p = 0.015) in average knowledge about sepsis, with Scheffe’s post hoc test indicating that the Cypriot students had a higher average knowledge than the Greek students (p = 0.016), while students from neither country were significantly different from Croatian students (both p > 0.05). Conclusions: This study showed the still limited knowledge of nursing students and the differences among the educational programs for nursing students. The educational curricula of nursing studies should increase the number of sepsis lectures and use innovative techniques.