To understand the growth response to drought, we performed a proteomics study in the leaf growth zone of maize (Zea mays L.) seedlings and functionally characterized the role of starch biosynthesis in the regulation of growth, photosynthesis and antioxidant capacity, using the shrunken2 mutant (sh2), defective in ADP-glucose pyrophosphorylase. Drought induced differential expression of 284 proteins overrepresented for photosynthesis, amino acids, sugar and starch metabolism, and redox-regulation. Changes in protein levels correlated with enzyme activities (increased ATP synthase, cysteine synthase, starch synthase, RuBisCo, peroxiredoxin, glutaredoxin, thioredoxin and decreased triosephosphate isomerase, ferredoxin, cellulose synthase activities, respectively) and metabolite concentrations (increased ATP, cysteine, glycine, serine, starch, proline and decreased cellulose levels). The sh2 mutant had a reduced ability to increase starch levels under drought conditions, causing soluble sugar starvation at the end of the night and impaired leaf growth. Increased RuBisCo activity and pigment concentrations observed in WT in response to drought were lacking in the mutant, which suffered more oxidative damage and recovered more slowly after re-watering. These results demonstrate that starch biosynthesis plays a crucial role in maintaining leaf growth under drought stress and facilitates enhanced carbon acquisition upon recovery.