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Abstract We report Magnetospheric Multiscale observations of oxygen ions (O+) during a coronal mass ejection (CME) in April 2023 when the solar wind was sub‐Alfvénic and Alfvén wings formed. For the first time, O+ characteristics are studied at the contact region between the unshocked solar wind and the magnetosphere. The O+ ions show energies between 100s eV and ∼30 keV. The possible sources are the ring current, the warm plasma cloak, and the ionosphere. The O+ ions exhibit bi‐directional streaming along newly‐formed closed field lines (CFLs), and dominantly anti‐parallel on earlier‐formed CFLs. Escaping O+ ions in the unshocked solar wind are observed. During the recovery phase, the O+ pitch‐angle distribution associated with flux tubes shows dispersion, indicating potential loss to the solar wind. Our results show escaping as well as trapped O+ ions in the region where a magnetic cloud, an Alfvén wing, and magnetospheric field lines are mixed.