In this study, the Metacognition in Mathematics (MIM) Scale developed by Fung and Leung (2017) was adapted to Turkish. The study was conducted in a working group of 355 secondary school students. In the confirmatory factor analysis (CFA) performed as a part of structure validity, the four-factor structure in the original MIM form was found to be confirmed in the Turkish culture. The fit indices obtained in the CFA performed on the four-factor structure were found to be within the limits of excellent or acceptable. In the reliability analysis, Cronbach alpha internal consistency coefficients were found to be 0.84 for the prediction dimension, 0.83 for the planning dimension, 0.84 for the monitoring dimension, and 0.84 for the evaluation dimension. The Cronbach alpha coefficient for the entire scale was found to be 0.91. In the item analysis, it was concluded that item correlations for all scale items exceeded the value criterion of 0.30. The results show the validity and reliability of the measurements obtained by the Turkish version of MIM.