Ternary copper(II) complexes of salicylaldehyde-histamine Schiff base (HL) and pyridyl ligands, viz. [Cu(bpy)(L)](ClO₄) (1) and [Cu(dppz)(L)](ClO₄) (2), where bpy is 2,2′-bipyridine (in 1) and dppz is dipyrido[3,2-a:2′,3′-c]phenazine (in 2), were synthesized, characterized and their DNA binding, photo-activated DNA cleavage activity and photocytotoxicity studied. The 1:1 electrolytic one-electron paramagnetic complexes showed a d-d band near 670 nm in aqueous DMF (1:1 v/v). The crystal structure of complex 1 showed the metal in CuN₄O distorted square-pyramidal geometry. Complex 2 intercalatively binds to calf-thymus (ct) DNA with a binding constant (𝐾_b) of ∼10⁵ M⁻¹. It exhibited moderate chemical nuclease activity but excellent DNA photocleavage activity in red light of 647 nm forming $^{\bullet}\text{OH}$ radicals. It showed remarkable photocytotoxicity in human cervical cancer cells (HeLa) giving IC₅₀ of 1.6 𝜇M in visible light (400-700 nm) with low dark toxicity. The photo-induced cell death is via generation of oxidative stress by reactive oxygen species.