Gulf countries and Malaysia are major destinations for labour migrants from South Asia. Despite their substantial economic contributions, these gains are often achieved at the expense of migrants’ health and well-being. Many South Asian migrants work in dirty, dangerous, and difficult (3-D) jobs and face exploitation, abuse, social isolation, and limited access to support services. These conditions may contribute to poor mental health, undermining productivity, socio-economic stability, remittance flows, and reintegration after return. Evidence on the mental health burden among South Asian migrants in the Gulf and Malaysia remains fragmented, highlighting the need for a systematic review to inform targeted interventions. Two key objectives of this review are to: (i) synthesise findings on mental illness, examine key social and structural determinants; and, (ii) identify gaps in support services both in home and destination countries for South Asian migrants. Prospero registration is available here: https://www.crd.york.ac.uk/PROSPERO/view/CRD420251271498 )