Kondo metal CePtAl₄Ge₂ exhibits long-range antiferromagnetic order below 2.3 K. Neutron powder-diffraction experiments reveal that Ce moments order antiferromagnetically with an incommensurate ordering wave vector k = (1.39, 0, 0.09). Inelastic neutron powder scattering experiments show a magnetic excitation at 14.5 meV, which corresponds to the first excited state due to the crystalline electric field splitting of the ground-state multiplet of Ce³⁺. The temperature and field dependence of the magnetization of CePtAl₄Ge₂ is consistent with a doublet ground state with a dominant |j_z = 1/2⟩ character and a first excited doublet |j_z = 3/2⟩ at 14.5 meV.