This study examined student teachers' perceptions of how well their Teacher Education (TE) had prepared them for 21st-century competencies, and how well they applied these competencies to their teaching. In addition, the study sought to identify best practices, major obstacles, and suggestions to achieve these competencies. The study was implemented in two universities and three universities of applied sciences in Finland that have TE programmes. This study used a mixed-method approach. Data were collected both quantitatively and qualitatively from student teachers (n = 227), who assessed 21st-century competencies with a structured questionnaire that included open-ended questions. Quantitative data analysis used descriptive statistics and correlations, while qualitative data analysis used content analysis. The study found that based on the student teachers' self-assessment, the student teachers achieved successfully 21st-century competencies despite differences between competencies. The best-achieved competency was 'Collaboration' and the least well-achieved was 'Global connections.' The study illustrated student teachers' perception of their success in applying 21st-century competencies to their teaching at schools. Answers to open-ended questions produced convincing evidence that courses involving collaborative and interactive learning, high quality, sufficient support, related 21st-century competencies, certain pedagogical methods used by teacher educators, and integrating theory and practice can contribute strongly to the development of student teachers' 21st-century competencies.