Optical frequency combs are fundamentally important in precision measurement physics, bringing unprecedented capabilities of measurements for time keeping, metrology, and spectroscopy. In this work, we investigate theoretically the formation of a form of frequency combs in cavity optomagnonics, in which a ferrimagnetic insulator sphere supports optical whispering gallery modes for both light photons and magnons. Numerical simulations of the optomagnonic dynamics show that a robust frequency comb can be obtained at low power under the bichromatic pumping drive, and the comb spacing is adjustable. Furthermore, the optomagnonic frequency comb structure has abundant non-perturbative features, suggesting that the magnon-induced Brillouin light scattering process in cavity optomagnonics may also exhibit phenomena similar to those in atomic–molecular systems. In addition to providing insight into optomagnonic nonlinearity, optomagnonic frequency combs may also provide the feasibility of implementing frequency combs based on spintronic platforms and may find applications for precision metrology based on magnonic devices.