ObjectiveThis study aimed to assess the prevalence and determinants of the triple burden of malnutrition among mother–child pairs in low-income and middle-income countries.DesignCross-sectional study.SettingLow-income and middle-income countries.ParticipantsWomen and children.Primary outcomeTriple burden of malnutrition (overweight/obese mother with undernourished and anaemic under 5 years child).MethodsData for this study were drawn from recent 22 low-income and middle-income countries Demographic and Health Surveys. A total weighted sample of 116 795 mother–child pairs was included in the study. STATA V.14.2 was used to clean, code and analyse the data. Multilevel logistic regression was employed to identify factors associated with the problem. Adjusted OR (AOR) with 95% CI and a p<0.05 was reported to indicate statistical association. Model fitness and comparison were done using intraclass correlation coefficient, median OR, proportional change in variance and deviance.ResultThe pooled prevalence of the triple burden of malnutrition among mother–child pairs was 11.39%. It showed statistically significant positive associations with mothers aged ≥35 years (AOR 2.25, 95% CI 2.08 to 2.44), family size >10 (AOR 1.17, 95% CI 1.08 to 1.26), delivery by caesarean section (AOR 1.93, 95% CI 1.83 to 2.03), the richest household (AOR 1.72, 95% CI 1.56 to 1.88), grand multiparous (AOR 1.62, 95% CI 1.46 to 1.81), age of child 36–47 months (AOR 1.77, 95% CI 1.64 to 1.90), at a p<0.05. Whereas breast feeding (AOR 0.94, 95% CI 0.89 to 0.99), married mothers (AOR 0.87, 95% CI 0.78 to 0.96), female children (AOR 0.88, 95% CI 0.84 to 0.92), improved toilet (AOR 0.23, 95% CI 0.17 to 0.29), improved source of drinking water (AOR 0.28, 95% CI 0.21 to 0.35), rural residents (AOR 0.66, 95% CI 0.62 to 0.69) had a contrasting relationship with the triple burden of malnutrition.ConclusionAbout 1 out of 10 households suffer from the triple burden of malnutrition in low-income and middle-income countries. This study revealed that several maternal, child, household and community-level factors have a significant impact on the triple burden of malnutrition among mother–child pairs.