We present results of magnetic neutron diffraction experiments on the codoped superoxygenated La2-x Srx CuO4+y (LSCO+O) system with x=0.09. We find that the magnetic phase is long-range ordered incommensurate antiferromagnetic with a Néel temperature TN coinciding with the superconducting ordering temperature Tc =40 K. The incommensurability value is consistent with a hole doping of nh ≈ 1 8 but in contrast to nonsuperoxygenated La2-x Srx CuO4 with hole doping close to nh ≈ 1 8 the magnetic-order parameter is not field dependent. We attribute this to the magnetic order being fully developed in LSCO+O as in the spin and charge ordered "stripe" compounds La1.48 Nd0.40 Sr0.12 CuO4 and La7/8 Ba1/8 CuO4.