In the title compound, C(17)H(20)Cl(2)N(4)O, the piperazine ring adopts a chair conformation and the dihedral angle between the pyridazine ring and the benzene ring is 36.3 (1)°. In the crystal, weak C-H⋯O and C-H⋯(N,N) inter-actions help to establish the packing, which also features short inter-molecular Cl⋯Cl contacts [3.331 (2) Å].