BackgroundDespite an increasing need for multisectoral interventions and coordinations for addressing malnutrition, evidence-based multisectoral nutrition interventions have been rarely developed and implemented in low-income and middle-income countries. To identify key determinants of undernutrition for effectively designing a multisectoral intervention package, a nutrition survey was conducted, by comprehensively covering a variety of variables across sectors, in Niassa province, Mozambique.MethodsA cross-sectional household survey was conducted in Niassa province, August–October 2019. Anthropometric measurements, anaemia tests of children under 5 years of age and structured interviews with their mothers were conducted. A total of 1498 children under 5 years of age participated in the survey. We employed 107 background variables related to possible underlying and immediate causes of undernutrition, to examine their associations with being malnourished. Both bivariate (χ2 test and Mann-Whitney’s U test) and multivariate analyses (logistic regression) were undertaken, to identify the determinants of being malnourished.ResultsPrevalence rates of stunting, underweight and wasting were estimated at 46.2%, 20.0% and 7.1%, respectively. Timely introduction of solid, semi-solid or soft foods to children of 6–8 months of age was detected as a determinant of being not stunted. Mother–child cosleeping and ownership of birth certificate were a protective factor from and a promoting factor for being underweight, respectively. Similarly, availability and consumption of eggs at the household level and cough during the last 2 weeks among children were likely to be a protective factor from and a promoting factor for being wasted, respectively.ConclusionTimely introduction of solid, semi-solid or soft foods could serve as an entry point for the three sectors to start making joint efforts, as it requires the interventions from all health, agriculture and water sectors. To enable us to make meaningful interprovincial, international and inter-seasonal comparisons, it is crucially important to develop a standard set of variables related to being malnourished.