Many dramatic changes have been observed in the quality and quantity of knowledge and skills, as well as in the form of access to and transfer of information in the 21st century. It is important to identify the skill levels of the classroom teachers who are responsible for educational activities in primary schools for maintaining an effective educational process. The aim of this study is to examine the classroom teachers' 21st century skills in terms of various variables. An explanatory sequential pattern of mixed research methods was used in the study. The quantitative data of the study were collected from 268 classroom teachers determined by convenience sampling method, and the qualitative data were collected from 20 classroom teachers determined by maximum sampling method. The quantitative data of the study were collected using the 21st Century Teaching Skills Scale developed by Orhan-Göksün (2016) and the qualitative data were collected through an interview form prepared by the researchers consisting of seven questions. The quantitative data were evaluated by descriptive statistics, Mann-Whitney U-Test and Kruskal Wallis H-test using SPSS 22 program. The qualitative data were analyzed by the content analysis method using Nvivo 11 program. The quantitative findings of the study revealed that the participants “generally” benefited from the 21st century teaching skills in the classroom. It was also found that they used confirmatory teaching skills at the most and flexible teaching skills at the least in the sub-dimensions of the scale. The results of the study showed that the 21st century skills of classroom teachers do not differ significantly in terms of age, gender, seniority in the profession and educational level. However, there were significant differences in terms of gender in the flexible teaching sub-dimension; in terms of age and seniority in the profession in technopedagogical and consenting skills sub-dimensions. The qualitative findings of the study revealed that the classroom teachers often reinforced the positive behaviors of their students, made the necessary work to ensure that students respect individual differences, kept observation records about the basic skills of their students, determine the classroom rules together with their students, prepared worksheets and authentic materials, used technological devices to enrich teaching and organized educational and social activities for students.