Mathematical connections are essential to emphasize in the learning process, to make students see mathematics as useful, relevant, integrated, and able to solve various mathematical problems. This study was conducted to analyze the comparison of achievement and improvement of students' abilities on mathematical connections based on learning model interventions. This comparative study used quasi-experimental types in three groups of students, namely 50 students who learned through the Connecting, Organizing, Reflecting, and Extending models with Realistic Mathematics Education (CORE RME), 49 students who learned through the CORE model, and 46 students who learned through the conventional model. The mathematical connections test is used as an instrument in this study. The finding in this study is that learning through the CORE RME model can facilitate students' mathematical connections abilities. This finding is based on the results of a survey that the achievement and improvement of the mathematical connections abilities of students who learned through the CORE RME model were better than the attainment and progress of the mathematical connections abilities of students who learned through the CORE model, and students who learned through the conventional model. Therefore, it is recommended for teachers to use the CORE RME model as an alternative to facilitate students' mathematical connection abilities.