High dropout rates in online courses, caused by potential factors such as financial issues, low motivation and poor self-regulation among learners, pose a significant challenge to the sustainable development of online education. Therefore, continuance of online courses has become a critical topic in both the academic and practical fields. By combining the Community of Inquiry framework (CoI) with Expectation-Confirmation Theory, this study introduces three new constructs--confirmed teaching presence (CTP), confirmed cognitive presence (CCP) and confirmed social presence (CSP)--into the research model to understand how confirmed expectations towards CoI determine online learners' course continuance intention. Utilizing a mixed-methods approach, the study conducted quantitative analysis on 409 learner surveys using partial least squares (PLS), followed by semi-structured interviews, which revealed the depth and breadth of the confirmed CoI expectations on learners' willingness to continue learning. Specifically, the quantitative results uncovered the differential effects of CTP, CCP and CSP on learners' course continuance intentions by elucidating the internal mechanisms. The interviews provided deeper insights by illuminating online learners' initial expectations as well as their pre-course and post-course expectations. The findings of the study not only provide evidence of the crucial role of confirmed expectations in shaping online learners' course continuance intention but also offer actionable recommendations for improving online course design and fostering lifelong learning.