As a part of development study in developing a relevant vocational course to improve student skills for meeting the industry requirement, this research aims to enhance collaborative mindset in CAD construction drawing course using the blended online learning platform. The flipped classroom strategy is employed to conduct the learning process with a project-based approach. The platform facilitates the learning process and changes the negative mindset with the positive ones, inside and outside the class. It provides a project showroom embedded on the website with comment tools for discussion, learning material, and sustainably developed tutorial video. The blended online platform is including WordPress content management system (CMS), Zoom, YouTube, Google for Education, Imgbb, WhatsApp SNS, and Efront learning management system (LMS), which combined into an integrated learning media for providing the needs of the learning methods used in the course with better benefits, accessible and easy to follow by the students. A study was conducted to discover students’ collaborative mindset improvement in two different classes, an experiment class B and a control class A. Class B consisted of 36 students use the blended online learning platform with a project-based flipped classroom strategy, and Class A use the regular learning model consists of 39 students. Data analysis was performed by descriptive analysis, paired sample t-test, and independent-sample t-test. The descriptive analysis showed collaborative mindset average scores of 70.90 in the pre-test and 73.91 in the post-test on a scale of 100 for class A. In contrast, class B collaborative mindset average scores are 70.28 and 79.93 for the pre-test and post-test, with an N-gain score of 0.3225, which means the collaborative mindset increased by 32.25% after being treated by applying the blended online learning platform for one month. The paired samples t-test analysis of the experiment class discovers a significant improvement of collaborative mindset with a highly significant correlation of 0.935 and Sig. 0.000 < 0.05 between pre-test and post-test. Moreover, the independent samples t-test revealed the two classes’ initial behaviors are equal with a tcount of 0.278 < ttable of 1.665 and the value of Sig. (2-tailed) 0.782 > 0.05 probability. In opposition, the posttest result asserts a significant difference of collaborative mindset between the experiment class and the control class with a tcount of 3.707 > ttable of 1.665 and the value of Sig. (2-tailed) 0.000 < 0.05. Based on all the analysis tests, it can be concluded that the blended online learning platform with project-based flipped classroom strategy is significantly enhancing students’ collaborative mindset. Furthermore, the future work is conducting the summative evaluation and developing the platform based on further evaluation.