The aim of this study is to investigate middle school students' competencies towards mathematical modelling and their views on this process in a learning environment designed with interdisciplinary modelling activities. Embedded experimental mixed design was used in the study. The study lasted 15 weeks with seventh grade students with control and experimental groups, including the application process and pre-test-post-test. The data of the research were obtained from mathematical modeling tasks, pre-opinion, and post-opinion forms for mathematical modeling. In the analysis of quantitative data, Wilcoxon signed ranks test and Mann Whitney U-test; In the qualitative, content analysis and thematic analysis were used. It was determined that there was a significant difference in favour of the post-test in all other competencies except the validating competence in the pre-test-post-test modeling competencies. In the qualitative analysis of the opinions of the experimental group students, it was found that mathematical modeling was efficient in associating mathematics with other disciplines and daily life after the learning process; It has been determined that it contributes positively to their success, understanding, interest and motivation.