We present an analysis of the influence of an external magnetic field on renormalons in a self-interacting theory lambda phi(4). For weak magnetic field region, using an appropriate expansion for the Schwinger propagators, we find renormalons as poles on the real axis of the Borel plane, of which the position do not depend on the magnetic field, but where the residues acquire in fact a magnetic dependence. In the strong magnetic limit, working in the lowest Landau level approximation, these new poles are no longer present. We compare the magnetic scenario with previous results in the literature concerning thermal effects on renormalons in this theory.