The response of a mixed system is determined by the proportions of the various ingredients that add up to one, not by the combination's total amount. This research aimed at examining the effects of blending ratio variation on the macro‐composition and sensory acceptability of dabi teff‐field pea‐based novel composite complementary flours. Standard methods (AOAC, 2016, Official Methods of Analysis of the Association of Official Analytical Chemists) were used to determine macronutrients. The sensory attributes were evaluated using a 5‐point hedonic scale. The ingredients were constrained at 0%–30% for field pea, 20%–35% for dabi teff, and 5%–20% for maize, while the remaining were set constant at 5% linseed, 15% oats, and 25% barley. D‐optimal was used to examine the effects of blending ratio variation on the responses. All the responses were significantly different (p < .05) among the blends except for fat content, ranging from 14.58% to 17.21% for protein, 4.22% to 5.59% fat, 2.01% to 2.60% ash, 2.68% to 3.96% fiber, 68.08% to 70.76% utilizable carbohydrate, and 378.82 to 386.9 kcal/100 g gross energy. The sensory acceptability score ranged from 3.4 to 4.4. The linear model was significant (p < .05) and adequate to describe variation in moisture, protein, and ash contents. An increase in the ratio of field pea significantly increased (p < .05) protein, ash, fiber, and energy. The interactive effect between dabi teff and field pea significantly increased the sensory acceptability of the blends. These findings showed that varied proportions of the ingredients had a significant effect on the responses, and were used to develop a wholesome product to combat protein‐energy malnutrition among children.