This invention provides supported catalysts comprising a carrier, phosphorus, at least one Group VI metal, at least one Group VIII metal, and a polymer. In the catalyst, the molar ratio of phosphorus to Group VI metal is about 1:1.5 to less than about 1:12, the molar ratio of the Group VI metal to the Group VIII metal is about 1:1 to about 5:1, and the polymer has a carbon backbone and comprises functional groups having at least one heteroatom. Also provided are a process for preparing such supported catalysts, as well as methods for hydrotreating, hydrodenitrogenation, and/or hydrodesulfurization, using supported catalysts.