Quantum anomalous Hall effect (QAHE) arises from the interplay between magnetic order and spin-orbit coupling, which opens up a topologically nontrivial band gap to host chiral edge states in the absence of magnetic field. So far, magnetic order of QAHE usually originates from partially filled transition-metal d orbitals or correlation-driven moiré bands. Here, we propose an experimentally accessible family of two-dimensional oxides, M₂DO₆ (M = Zn, Cd; D = Se, Te), that can realize QAHE from the half-filled O-2p orbital induced spontaneous ferromagnetism. In M₂DO₆ monolayers, spin-polarized Dirac points appear at K/K^′ valleys and along Γ-K/Γ-K^′ lines. C₃ rotational symmetry then generates eight symmetry-related crossings in the first Brillouin zone. Upon gap opening by spin-orbit coupling, each massive Dirac point contributes half Chern number, resulting in a high-Chern-number QAHE phase with C=4. We establish cation deintercalation as a general strategy to activate O-2p ferromagnetism in oxides. Our finding provides a route to realize QAHE from O-2p ferromagnetism and offers design principles applicable to oxygen-based magnetic topology platforms beyond conventional d-electron systems.