The development of higher-order thinking skills requires appropriate learning techniques. Project-based learning and integrated learning are learning models that can be used for this purpose. This study aimed to evaluate the contribution of project-based learning and integrated learning to the HOTS development of students in 6 private schools. The sample in this study was high school-level students who were determined by purposive sampling and random sampling techniques. The number of samples is 500 students. The instruments used are a measurement scale and a questionnaire with open questions. Data analysis was performed using the partial least squares technique. Based on the results of measurement scale data analysis, it was found that project-based learning combined with integrated learning showed a significant contribution to the development of students' HOTS. Project-based learning and integrated learning provide flexibility for students to study according to their characteristics so that the application of the student-center approach is practical. In addition, students are more motivated to undergo the learning process with this model approach because of the challenges of producing quality projects. [For the full proceedings, see ED654100.]