Nowdays, for most people, the usage of the internet is unavoidable. The COVID-19 pandemic has further increased internet usage, which might result in an even greater prevalence of its misuse and potentially affect the mental health of individuals. The goal of this masters' thesis is recognize and to discern the effect of the COVID-19 pandemic on the usage of internet and on the mental health of an individual, thus enabling the future development of applicable regulatory framework regarding the protection of the user in similar circumstances and to mitigate negative consequences on one's mental health. To that end, an extensive overview of the scientific literature and relevant research was conducted to discern the effect of the COVID-19 pandemic on the usage of internet and on the mental health, aiming at the further advancement of social and educational science and practice. The aforementioned methodology has enabled an extensive oveview of the field of research, while also enabling the recognition of the potential problems and the drawing of relevant conclusions. During the COVID-19 pandemic, there was a significant increase in the usage of the internet, especially on social media platforms and in online video games. Prevelance of the problematic use of the internet also increased during the pandemic with the main predictors being depression, anxiety, stress, loneliness, and a lack of scocial support. Differences among individuals, access to support, the quality of interpersonal relations and mental health in general play an important role in one's coping with the pandemic and how they use the internet in that regard. The purpose and motivation for using internet are important factors that influence the pychological wellbeing and severity of the problematic usage of internet. It is important to note that the results of the research vary, further highlighting the complexity of this topic. One of the crucial conclusions of this master's thesis is that the lack of consensus regarding the very definition of the internet addiction makes it difficult to research and to obtain understanding of this problem which is evermore prevalent in the modern society. Therefore, it is important to point out that additional research is needed in order to obtain deeper insight into the causes of the problematic usageof the internet in the similar circumstances, as well as the necessity of tackling this problem among experts from the adjacent branches of expertise.