Interfaces of ferromagnetic/organic material hybrid structures refer to the spin interface that governs physical properties for achieving high spin polarization, low impedance mismatch, and long spin relaxation. Spintronics can add new functionalities to electronic devices by taking advantage of the spin degree of freedom of electrons, which makes understanding the dynamic magnetic properties of magnetic films important for spintronic device applications. Our knowledge regarding the magnetic dynamics and magnetic anisotropy of combining ferromagnetic layer and organic semiconductor by microwave-dependent magnetic measurements remains limited. Herein, we report the impact of an organic layer on the dynamic magnetic behavior of nickel/rubrene bilayers deposited on a Si(100) substrate. From magnetic dynamic measurements, opposite signs of effective magnetic fields between the in-plane (IP) and out-of-plane (OP) configurations suggest that the magnetization of Ni(x)/rubrene/Si prefers to coexist. A shift in OP resonance fields to higher values can mainly be attributed to the enhanced second-order anisotropy parameter K2 value. Based on IP measurements, a two-magnon scattering mechanism is dominant for thin Ni(x)/rubrene/Si bilayers. By adding a rubrene layer, the highly stable IP combined with the tunable OP ferromagnetic resonance spectra for Ni(x)/rubrene/Si bilayers make them promising materials for use in microwave magnetic devices and spintronics with controllable perpendicular magnetic anisotropy.