IntroductionThe role of primary caregivers in setting the foundation for a child’s oral health throughout life is well recognised. Due to the dominant behaviour-based approach, research to date has mainly focused on exploring individual primary caregivers’ oral health knowledge and behaviours. A social science approach involving social practice theories moves beyond individual attitudes, behaviour and choices to offer a better understanding of the ways in which collective activity relates to health. This qualitative metasynthesis will involve an interpretive synthesis of data found in published qualitative literature from developed countries. The aim of the metasynthesis is to identify social practices in families from published qualitative research with caregivers on preschool children’s oral health.Methods and analysisThis is a protocol for qualitative metasynthesis. The following databases will be used: MEDLINE, EMBASE, Global Health and Dentistry & Oral Sciences Source (DOSS) using the web-based database search platform Ovid, Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Scopus. The research team has determined search strategies by using relevant key terms. Qualitative studies published in English language on family factors related to preschool children (aged 0–5 years) from developed countries (2022 United Nations classification) will be included. Qualitative data analysis will involve thematic analysis of the reported factors influencing oral health of preschool children, from the perspective of social practice theory. Researchers will use NVivo software for organising and managing the data.Ethics and disseminationNo ethics approval is required, as this study does not involve human subjects. Findings will be disseminated through professional networks, conference presentations and submission to a peer-reviewed journal.