This study sought to develop a self-report instrument to be used in the assessment of the project competences of college students engaged in online project-based learning. Three scales of the KIPSSE instrument developed for this study, namely, the knowledge integration, project skills, and self-efficacy scales, were based on related theories and the analysis results of three project advisor interviews. Those items of knowledge integration and project skill scales focused on the integration of different disciplines and technological skills separately. Two samples of data were collected from information technology-related courses taught with an online project-based learning strategy over different semesters at a college in southern Taiwan. The validity and reliability of the KIPSSE instrument were confirmed through item analysis and confirmatory factor analysis using structural equation modeling of two samples of students' online response sets separately. The Cronbach's alpha reliability coefficient for the entire instrument was 0.931; for each scale, the alpha ranged from 0.832 to 0.907. There was also a significant correlation (r = 0.55, p < 0.01) between the KIPSSE instrument results and the students' product evaluation scores. The findings of this study confirmed the validity and reliability of the KIPSSE instrument. The confirmation process and related implications are also discussed.