Type-IV two-dimensional (2D) magnetism-a newly classified collinear magnetic phase featuring nonrelativistic spin degeneracy and spin-orbit-coupling-induced momentum-dependent spin splitting-extends the symmetry classification of collinear magnets, opening new opportunities for unconventional topological quantum states. Here, we reveal that the recently proposed two-dimensional type-IV 2D magnet MgCr₂O₄ hosts an intrinsic higher-order topological insulating phase, featuring C_3z-protected corner states and a nontrivial rotational topological invariant of χ⁽³⁾ = {-2,4} with a quantized fractional corner charge of 4e/3. Spin-orbit coupling breaks the spin-degeneracy-enforcing symmetry [C₂||M_z] while preserving the crystalline C_3z rotational symmetry that protects the higher-order topological phase, thereby enabling spin splitting to coexist with the nontrivial topology. Furthermore, the higher-order topological phase remains intact throughout a wide range of biaxial strains without band-gap closing and topological phase transition, demonstrating the robustness of the symmetry-protected topological state against external perturbations. Our work establishes a direct connection between type-IV magnetic system and higher-order topology, providing a new route for symmetry-engineered magnetic topological quantum states.