The study aims to examine the relationship between anxiety and psychological needs of high school students during the COVID-19 pandemic period. The fact that the COVID-19 virus poses a threat to mental health as well as physical health, the effects of the pandemic period on the psychological needs and anxiety level of adolescents, especially in a critical developmental stage, and the scarcity of studies concerning adolescent mental health in this period, constituted the purpose of the current study. The quantitative (N = 502) and qualitative data (N = 29) of the study, in which triangulation design was used, were collected from high school students studying in the Southeast of Turkey. In the quantitative part of the research Multiple Linear Regression was implemented and content analysis was used in the qualitative part. The results indicate that love, belonging and power, which are subdimensions of basic psychological needs, are significant predictors of anxiety level. Additionally, it is seen that the need for freedom subdimension is the least predictive variable for the anxiety level. It is concluded that there are moderate negative and significant relationships between the general and subdimensions of basic psychological needs and the level of state anxiety. In this sense, it has been found that the level of anxiety tends to decrease as the level of the satisfaction of basic psychological needs increases. The results in the qualitative analysis part largely overlap with the results in the quantitative part. Suggestions based on the findings of the study are made to researchers.