Supported MoS2/γ‐Al2O3 and Ni‐MoS2/γ‐Al2O3 as well as unsupported Ni‐MoS2 were investigated in the hydrodenitrogenation (HDN) of quinoline in the presence of dibenzothiophene (DBT). The supported oxide catalyst precursors had a well‐dispersed amorphous polymolybdate structure that led to the formation of a highly dispersed sulfide phase. In contrast, the unsupported catalyst precursor consisted of a mixture of nickel molybdate and ammonium nickel molybdate phases that formed stacked sulfide slabs after sulfidation. On all catalysts, the reaction pathway for the removal of N in quinoline HDN mainly followed the sequence quinoline→1,2,3,4‐tetrahydroquinoline→decahydroquinoline→propylcyclohexylamine→propylcyclohexene→propylcyclohexane. The hydrodesulfurization of DBT proceeded mainly by direct desulfurization towards biphenyl. For both processes, the activity increased in the order MoS2/γ‐Al2O32/unsupported2/γ‐Al2O3. The promotion of the MoS2 phase with Ni enhances the activity of the unsupported catalyst to a greater extent than the supported one. However, the multiply stacked unsupported Ni‐MoS2 exhibited lower rates than Ni‐MoS2/γ‐Al2O3 because of its lower dispersion. I want to break free (from your nitrogen): Ni and Al2O3 exert particular effects on the physicochemical and kinetic features of molybdenum oxide species and the corresponding MoS2 phase. The support maximizes the concentration of active sites, whereas the promoter changes their intrinsic activity. In turn, the support also influences the promotion mechanism.