This paper analyzes the impact of a Course Transformation process based on a Flipped Classroom strategy on Chilean Engineering students' attitudes toward university-level mathematics. The Attitudes Toward Mathematics Inventory (ATMI) questionnaire was applied as both pre- and post-test to 76 students in three mathematic courses (Calculus I, Calculus II and Elements of Algebra for Computing) at Universidad Catolica de Temuco's Faculty of Engineering which adopted a flipped classroom method. The results showed a significant positive change in the perceived value of mathematics in the four ATMI categories (P < 0.05) with different effect sizes after the implementation of the flipped classroom and active learning strategies. The results suggest that the implementation of transformed courses using a Flipped Classroom method has a positive effect on students' attitudes toward Mathematics, especially in those who come from families with lower economical income.