Increasing evidence has shown that the COVID-19 outbreak has impacted adolescents' mental health. Utilising a mixed-method design, the current study examined a total of 518 adolescent perspectives (60% female), in Scotland, on what "has" and "could" help their mental health in the context of COVID-19. A reflexive thematic analysis revealed three themes in relation to what "has" helped adolescents' mental health since the COVID-19 outbreak. These related to findings about the value of: (1) engaging in recreational activities, (2) engaging with friends, and (3) the disruption to schooling. The remaining four themes related to what could have helped adolescents mental health and wellbeing since the COVID-19 outbreak. These focussed on (1) better support: in relation to mental health; school work; and communication, (2) contact with friends, and (3) more opportunities for recreational activities. Males were more likely to report recreational activities "had" helped and less likely to report better support "could" have helped. Adolescents who reached clinical threshold for depression and anxiety and those with elevated PTSD-like symptoms about COVID-19 were more likely to state more support "could" have helped, and adolescents who reached clinical threshold for depression were "less" likely to report that friends could have helped their mental health. The findings may inform mental health policy and interventions in the recovery from the COVID-19 pandemic.