This study explored the possibility of using Facebook in online instruction as an auxiliary tool for promoting interaction. The goal was to increase interaction and intimacy among learners to reduce the feeling of isolation and increase learner satisfaction. This research adopted an empirical design and recruited a total of 64 students from two classes. The classes were taught using a blended learning mode. Asynchronous instructional activities were designed according to the five-stage model proposed by Salmon (2003). We collected data from both Facebook and the online learning platform. According to the research findings, social presence, attitude toward collaborative learning, learning satisfaction, and learning outcomes were positively related with statistical significance. In addition, the use of Facebook promoted learners' social presence and learning satisfaction. The impact of social presence on the attitude toward collaborative learning and learning outcome was not significant. However, social presence had a positive impact on learning satisfaction. The results of this research can be used to develop instructional designs and strategies for online adult learners.