Maize is diagnosed as a heavy metal (HM) accumulator, while the tolerance mechanism is not sufficiently known. A hydroponic experiment was performed to test the ability of maize plants to tolerate and accumulate Cu. Excess copper treatments (ECu; 5 and 10 μM CuSO₄) considerably reduced plant growth, photosynthetic pigments, ascorbate peroxidase (APX), and guaiacol peroxidase (POD) activity. However, ECu significantly enhanced catalase (CAT) activity. ECu treatments reduced the leaf membrane integrity as indicated by increasing malondialdehyde (MDA) content in leaves. Proline and phenolic contents were considerably increased in maize organelles by ECu toxicity. ECu treatments considerably stimulated free amino acid (FAA) accumulation, total-soluble proteins (TSPs), and K in shoots, whereas these parameters did not change in the roots. Applications of CuSO₄ did not affect the accumulation of total soluble sugars (TSSs) in shoots, while this accumulation enhanced in roots. CuSO₄ treatments significantly increased the Cu concentration and uptake but decreased the Cu translocation factor (TF) and bioaccumulation factor (BF). Structural components such as cell wall components, proteins, lipids, and sugars were affected by ECu stress, as shown by infrared spectroscopy (FT-IR) analysis. These results give a new insight into the strategy, which maize can use to treat the Cu-polluted environment as Cu accumulates within seedling tissues and the seedling can protect itself from ECu stress.