Improved food availability and a growing economy in Tanzania may insufficiently decrease pre-existing nutritional deficiencies and simultaneously increase overweight within the same individual, household or population, causing a double burden of malnutrition (DBM). We investigated economic inequalities in DBM at the household level, expressed as a stunted child with a mother with overweight/obesity, and the moderating role of dietary diversity in these inequalities. We used cross-sectional data from the 2015-2016 Tanzania Demographic and Health Survey. A nationally representative survey. Totally, 2867 children (aged 6-23 months) and their mothers (aged 15-49 years). The mother-child pairs were categorised into two groups based on dietary diversity score: achieving and not achieving minimum dietary diversity. The prevalence of DBM was 5·6 % (sd = 0·6) and significantly varied by region (ranging from 0·6 % to 12·2 %). Significant interaction was observed between dietary diversity and household wealth index ( < 0·001). The prevalence of DBM monotonically increased with greater household wealth among mother-child pairs who did not achieve minimum dietary diversity ( < 0·001; however, this association was attenuated in those who achieved minimum dietary diversity ( = 0·16), particularly for the richest households ( = 0·44). Analysing household wealth index score as a continuous variable yielded similar results (OR (95 % CI): 2·10 (1·36, 3·25) for non-achievers of minimum dietary diversity, 1·38 (0·76, 2·54) for achievers). Greater household wealth was associated with higher odds of DBM in Tanzania; however, the negative impact of household economic status on DBM was mitigated by minimum dietary diversity.