Background: Adolescence is a time of significant physical and social change, leading to potential mismatches between physical and social maturity, which may contribute to emotional distress and antisocial behaviors. The purpose of this study was to investigate the impact of cognitive therapy focused on mindfulness and therapy centered on acceptance and commitment on anxiety stemming from the Covid-19 pandemic and the cognitive regulation abilities of adolescents in Kermanshah, over a two-month follow-up period. Method: This randomized clinical trial, conducted in 2022, involved 45 teenagers from Kermanshah, who were allocated into three different intervention groups using a stepwise cluster sampling method. Group 1 (15 participants) received cognitive therapy centered on mindfulness, Group 2 (15 participants) underwent acceptance and commitment therapy, and Group 3 (15 participants) served as the control. The Corona Virus Anxiety Scale and the Cognitive Emotion Regulation Questionnaire (CERQ) were the assessment tools used, and the data were processed using SPSS version 26. Findings: The study’s results revealed that both mindfulness-based cognitive therapy and acceptance and commitment therapy significantly alleviated Covid-19-related anxiety and improved cognitive regulation strategies, both adaptive and maladaptive, when compared to the control group. Conclusion: The study supports the use of mindfulness-based cognitive therapy and acceptance and commitment therapy as effective, enduring strategies for reducing Covid-19-related anxiety and enhancing cognitive regulation among adolescents, making them valuable in health and therapeutic contexts.