In this paper, we propose a system that can capture and assess users' emotional status and provide support. The system includes a user profile database, an expert knowledge rule base, an education material database, and a portable emotion-sensing module. A user answers standardized questionnaires and visual analogue scales regarding to different emotions including depression, anxiety and stress, while recording daily activities and contextual factors leading to mood change through the portable emotion-sensing module in real time. The portable emotion-sensing module stores these variables in the cloud-based user profile database via Wi-Fi. The expert knowledge rule base in the cloud server receives values and distributing patterns of the variables to determine the corresponding mood symptoms and their severity. The educational material database, based on mindfulness-based cognitive therapy, returns guidance and encouragements to the portable emotion sensing module through the internet to provide the user with real-time support. In the focus group testing, we invited twenty medical professionals and ten graduate school students to evaluate the system. Preliminary results showed that participants found the system helpful in achieving better awareness of their ever-changing emotional states, and that mindfulness-based audio guidance indeed helped them reduce stress and negative emotions. Subsequent pilot studies on patients with mild to moderate depression will help elucidate the clinical feasibility and efficacy of the proposed system.