Inadequate intake of age-specific energy and nutrients is among the prime immediate causes of child malnutrition. Thus, this study aimed to determine the energy, protein and Fe densities of pre-processed dabi teff-field pea-based optimised novel complementary flour and its contribution to daily energy and nutrients demand by 6–8, 9–11 and 12–23 month-old children. The optimal formula at overall optimisation was identified to be 34·66 % dabi teff, 25 % barley, 15 % oats, 15·34 % field pea, 5 % linseed and 5 % maize with response values of 15·74 % protein, 5·09 % fat, 2·26 % ash, 2·88 % fibre, 73·05 % carbohydrate, 1591·72 kJ/100 g (380·43 kcal/100 g) energy, 32·21 mg/100 g Fe, 77·51 mg/100 g Ca and 2·59 mg/100 g Zn. The energy density of the optimised novel complementary flour was 1·27 kcal/g which fulfilled the Pan American Health Organization/WHO recommendation (≥ 0·8 kcal/g), protein density was 4·14 g/100 kcal and the Fe density was 8·47 mg/100 kcal, which was 2·12 to 10·59 times higher than the recommended value where the optimal had demonstrated to contribute more than 100 % of the daily energy and protein demand and notably more than 200 % of daily Fe demand at moderate bioavailability (0·8–4 mg/100 kcal). These findings showed that the daily recommended dietary allowance for energy, protein and Fe could be attained by the developed dabi teff-field pea-based optimised novel complementary flour and its contribution to the children’s daily energy and nutrients demand met the standard, where the product can be used as food-based nutrition intervention to manage protein-energy malnutrition and Fe deficiency anemia in children sustainably.