Background This protocol outlines a systematic review examining how dyadic methodologies have been applied in studies of parent/carer–adolescent interactions over the past 15 years (2010–2025). Dyadic approaches provide unique insights into relational dynamics by capturing mutual influence between individuals. Despite increasing use in psychological and developmental research, no comprehensive synthesis currently focuses specifically on parent/carer–adolescent dyads. Methods The review will identify and analyse empirical studies that use parent/carer–adolescent dyadic methods to explore emotional, behavioural, and relational outcomes within family contexts. It will map methodological trends, theoretical frameworks, populations studied and consider author-led perspectives on the value these methods bring. Together, offering an overview of how dyadic approaches have been applied and facilitated new knowledge on relational dynamics in this field. Results The review will generate a synthesis of existing dyadic research on parent/carer–adolescent interactions, highlighting patterns in methodology, theory, study design and inform new outcomes. Conclusions Insights from this review will support the methodological planning and provide an evidence base for the design of the study Mental Health and Relationships during Transition through Adolescence to Adulthood, advancing understanding of relational influences on young people’s mental wellbeing during the transition to adulthood. In particular, the review will address learnings from the application of dyadic methodologies in studies examining parent/carer–adolescent interactions. These insights will strengthen the study’s capacity to investigate relational processes and advance understanding of how family and friend relationships shape young people’s mental wellbeing during the transition to adulthood.