Research demonstrates that young people value mental health support that is tailored to their needs and preferences, rather than a "one size fits all" offer, which is often not equitably accessible (National Children's Bureau, 2021). Understanding young people's lived experiences across different sociocultural contexts is important. The aim of this research was to conduct an international qualitative study on the views of young people with lived experience and professionals, on proposed aspects of personalised support for anxiety and/or depression. Participatory action focus groups were conducted with N = 120 young people with lived experience of anxiety and/or depression (14-24 years) and with N = 63 professionals in Brazil, India, Kenya, Pakistan, Portugal, South Africa, Turkey, and the United Kingdom. Data were analysed using the rigorous and accelerated data reduction (RADaR) technique. Overall, although some country-specific differences were found in terms of what aspects of support young people found to be most important, individual preferences were considered stronger, furthering the view that support should be personalised to the needs of the individual young person. Young people experiencing anxiety and/or depression should be able to choose for themselves which aspects of support they would prefer in their own care and support plans, with families and mental health professionals providing guidance where appropriate, rather than removing the young person from the decision-making process altogether. It should also be ensured that the aspects of personalised support can be understood by young people and professionals from different contexts, including marginalised and minoritised groups and communities.