An estimated 14.2% (9.34 million people) of people living in the UK in 2019 were international migrants. Despite this, there are no large-scale national studies of their healthcare resource utilisation and little is known about how migrants access and use healthcare services. One ongoing study of migration health in the UK, the Million Migrants study, links electronic health records (EHRs) from hospital-based data, national death records and Public Health England migrant and refugee data. However, the Million Migrants study cannot provide a complete picture of migration health resource utilisation as it lacks data on migrants from Europe and utilisation of primary care for all international migrants. Our study seeks to address this limitation by using primary care EHR data linked to hospital-based EHRs and national death records. Our study is split into a feasibility study and a main study. The feasibility study will assess the validity of a migration phenotype, a transparent reproducible algorithm using clinical terminology codes to determine migration status in Clinical Practice Research Datalink (CPRD), the largest UK primary care EHR. If the migration phenotype is found to be valid, the main study will involve using the phenotype in the linked dataset to describe primary care and hospital-based healthcare resource utilisation and mortality in migrants compared to non-migrants. All outcomes will be explored according to sub-conditions identified as research priorities through patient and public involvement, including preventable causes of inpatient admission, sexual and reproductive health conditions/interventions and mental health conditions. The results will generate evidence to inform policies that aim to improve migration health and universal health coverage.