Substrate package-integrated oxide capacitors and related methods are disclosed herein. An example apparatus including a first layer and a thin film capacitor including a second layer on the first layer, the second layer defining a plurality of openings and a third layer disposed on the first layer and in the plurality of openings, the second layer and the third layer corresponding to electrodes of a capacitor and a fourth layer disposed between the first layer and the second layer, the third layer including an oxidized material, the third layer forming a dielectric of the capacitor.