Background: Arts-based methodologies can be beneficial to identify different representations of stigmatized topics such as mental health conditions. This study used a theater-based workshop to describe manifestations, representations, and potential causes of depression and anxiety as perceived by adolescents and young adults. Methods: The theater company Teatro La Plaza conducted three online sessions with a group of adolescents and another with a group of young adults from Lima, Peru. The artistic outputs, which included images, similes, monologues, and narrations, were used to describe the experiences of depression and anxiety symptoms following a content analysis using posteriori categories. Results: Seventeen participants joined the sessions. The artistic outputs showed: physical, behavioral, cognitive, and emotional manifestations of depression and anxiety; a perception that both disorders have a cyclical nature; and an awareness that it is often difficult to notice symptom triggers. The mandatory social isolation due to the COVID-19 pandemic was highlighted as an important symptom trigger, mostly linked to anxiety. Conclusions: The findings are consistent with the literature, especially with regard to the manifestations, representations, and potential causes that trigger depression and anxiety. Using arts-based methods allowed adolescents and young adults to expand the articulation of their representations of mental disorders.