Aim To map and compare site-specific cancer mortality for Belgians and five of the largest immigrant groups in Belgium, and to look into the role of socio-economic position (SEP) and urbanisation. Methods We use linked Belgian census and register data for the period 2001–2011. Mortality from common cancer sites is studied for Belgians and individuals with a migrant background from Italy, France, the Netherlands, Morocco and Turkey aged 40 to 69. We use indirect standardisation and Poisson regression modelling, taking into account the effect of age, urbanisation and SEP. First- (FG) and second-generation (SG) immigrants are included. Results There is marked diversity in cancer mortality levels by migrant background, with oft-lower levels for FG Moroccan and Turkish immigrants, and levels usually closer to those of Belgians for European immigrants. Small increases are commonly observed by generation, although less clearly so for stomach and liver cancer. SEP plays an important role in the patterning of cancer mortality by migrant background. Conclusion Migrant background is associated with differences in site-specific cancer mortality levels in Belgium. The observed role of SEP warrants special attention to the most vulnerable socio-economic groups.