Background: Adolescents' opportunities for social progress have been negatively impacted by the COVID-19 epidemic. Education ,physical and general wellbeing are negativelyaffected . Action must be taken immediately to lessen the long-term effects of the epidemic and safeguard adolescents' futures. The aim of the study: To evaluate the effectiveness of web-based psychoeducational interventions on adolescents' knowledge and future anxiety during Covid-19 outbreak. Subjects and Method:  A quasi-experimental research design was used in this study. A purposive  sample of 52 adolescents from Tanta city in Algharbia Governorate was included in the study. This study was an online study that used Google forms.Tools:Three  tools were utilized: Tool I: Adolescents' knowledge regarding covid-19questionnaire , Tool II: Perceived Stress Scale – 10, and Tool III: Future anxiety scale. Results: The majority of the studied adolescents  had poor knowledge levels regarding COVID-19 pre the psychoeducational interventions, while all the studied adolescents had good knowledge post the  psychoeducational interventions.There was a decrease in the the studied adolescents' perceived stress  and  future anxiety  levels during COVID-19 post the psychoeducational interventions.And also, a moderate negative correlation between the studied adolescents' knowledge, their perceived stress and future anxiety post the  psychoeducational interventions Conclusion: The present study highlighted that web-based psychoeducational interventions effectively increased adolescents' knowledge regarding Covid- 19 and decreased their stress and future anxiety levels. Recommendation: Further research design  is needed to determine the psychological wellbeing of adolescents during COVID- 19 as well as reinforce the appropriate measures to maintain their mental health.