BackgroundThere is no consensus on how the disruption or maintenance of heritage culture and language affect mental health outcomes in adolescents with a migrant (also known as “immigrant” or “international migrant”) background. Even though previous literature reviews have investigated the association between acculturation and mental health in migrants, none have explicitly focused on adolescents.ObjectiveThe aim of the scoping review described in this protocol is to understand (1) the focus, scope, and nature of quantitative empirical research investigating heritage cultural maintenance, including linguistic maintenance, and mental health outcomes in adolescents with a migrant background worldwide and (2) the potential effects of cultural and linguistic maintenance or disruption on migrant adolescent mental health outcomes.MethodsA total of 11 key electronic health, medical, social science, and language databases (APA PsycArticles Full Text; Embase Classic+Embase; Ovid MEDLINE All and Epub Ahead of Print, In-Process, In-Data-Review and Other Non-Indexed Citations and Daily; Ovid MEDLINE All; APA PsycInfo; University of Melbourne full-text journals; Science Citation Index Expanded; Social Sciences Citation Index; Arts & Humanities Citation Index; Scopus; Linguistics and Language Behavior Abstracts) were searched. Databases were searched without time restrictions from the beginning of their coverage. Publication date, location, and quantitative study design (except for literature reviews) were not restricted; however, the search was only conducted in English. Data from included studies will be extracted using a template with predefined data items, and results will be summarized in a structured, narrative summary.ResultsA search was conducted on April 20, 2021, returning 2569 results. We are currently at the final stages of screening titles and abstracts of our search results, which will be followed by a full-text review and the data extraction of included studies. We expect to submit the full review for publication by the end of 2023.ConclusionsThe scoping review aims to provide a better understanding of existing research on the association between cultural (including linguistic) maintenance and mental health in migrant adolescents. It will help identify gaps in the existing literature and develop hypotheses that could inform future research, eventually facilitating the development of targeted prevention initiatives and improving migrant adolescents’ well-being.International Registered Report Identifier (IRRID)DERR1-10.2196/40143