The interaction between light and excitons in van der Waals materials offers new avenues for exploring strong coupling in quantum systems. Exciton-polaritons, arising from the coherent hybridization of excitons and photons, provide a unique platform for studying collective interactions, optical anisotropy, and tunable responses in low-dimensional structures. This work investigates the self-hybridization of photonic and excitonic modes in a waveguide based on the two-dimensional antiferromagnetic semiconductor CrSBr. Using angle-resolved photoluminescence and numerical modeling, we demonstrate that the pronounced anisotropy of exciton localization along the crystallographic b-axis leads to strong interaction with the waveguide mode. The observed anticrossing of dispersion curves is quantitatively described by a coupled oscillator model with a coupling strength of ~185 meV, providing direct evidence for the formation of self-hybridized exciton-polaritons. In the orthogonal polarization, no such interaction occurs, and only directional waveguide emission is detected. These findings pave the way for miniaturized polaritonic devices based on van der Waals magnets, where light matter interaction can be controlled by both waveguide geometry and magnetic order.