This dissertation investigates novel techniques that enable better management of cognitive well-being in order to improve mental well-being in the workplace. There is a strong link between cognitive well-being and mental well-being. Humans rely on various cognitive processes to perform daily tasks as well as emotional regulation. In the meantime, our cognitive resources are also consumed and gradually diminish when we perform those tasks. If not replenished properly, impairment in our cognitive health will have adverse effects on our task performance and ultimately on our mental health. Particularly, in the workplace, not only the tasks themselves but also other moderating factors put strain on our cognitive processes. As a result, the fluctuations in our cognitive well-being is even more evident and rapid, and individuals may sometimes fail to notice the early signs of declining cognitive health. This further underlines the importance of frequent assessments of cognitive well-being and early interventions in the workplace in order to keep our brain and mind healthy. Numerous methods have been developed to help individuals assess their cognitive well-being and the moderating factors. Different interventions have also been designed to help manage workers' cognitive well-being. However, these methods tend to be intrusive or burdensome, which limit the adoption of these technologies and their user retention. Therefore, there is a need for more automatic, unobtrusive methods that can assist workers in managing their cognitive well-being. The dissertation aims to investigate scalable techniques and systems that support cognitive well-being management, particularly in the context of work environments, including unobtrusive and continuous cognitive well-being measurements, identification of moderating factors, and personalized interventions. To gain insights into the efficacy of and workers' reactions to these technologies, I also conducted a number of studies to evaluate the techniques and systems I developed. I hope that this dissertation will lay the groundwork for advancing current intelligent cognitive well-being management technologies and ultimately better support individuals' cognitive and mental well-being in the workplace.