Blended synchronous learning (BSL) has become increasingly prominent in lifelong education due to its flexibility in enabling simultaneous onsite and online participation. However, enhancing the experience and satisfaction of adult learners in this context remains a challenge. This study primarily used structural equation modelling to examine the interrelationships among key factors that contribute to learner satisfaction. Data were collected from an online survey of 494 remote adult learners, reflections from 27 learners, and interviews with 23 learners, all in a BSL context at a Chinese open university. The results indicated that the perception of technological effectiveness (TE) significantly and positively influenced teaching presence (TP), social presence (SP), self-regulated learning presence (SRLP), cognitive presence (CP), and overall satisfaction (SAT). SP acted as a crucial mediator between TP and both SRLP and CP, as well as SAT. SRLP positively impacted CP, which in turn positively affected SAT. The influence of TE, SP, SRLP, TP, and CP on SAT was observed in descending order of impact. Theoretically, this study enhances the Community of Inquiry framework by exploring the interrelationships among its dimensions within the context of adult BSL learning, emphasizing the critical role of social presence in promoting learning satisfaction. The study identifies three key factors for optimal BSL implementation: the necessity of a stable and reliable technological infrastructure, the importance of cultivating a strong sense of social presence as a central element of effective pedagogical strategies, and the need to emphasize the development of self-regulated learning abilities among remote adult learners.