[en] We present a detailed theoretical study of oxygen molecules in high rotational states (molecular superrotors) interacting with an external magnetic field. The system shows rich dynamics, ranging from a spin-selective splitting of the angular distribution over molecular alignment to an inversion of the rotational direction. We find that the observed magneto-rotational effects are due to a spin-mediated precession of the orbital angular momentum around the magnetic field. Analytical expressions for the precession frequency in the limits of weak and strong magnetic fields are derived and used to support the proposed mechanism. In addition, we provide the procedure for a numerical treatment of oxygen superrotors in an external magnetic field. (paper)