The aim of this study was to synthesize a novel catalyst for urea oxidation and to test a stacked membraneless direct urea fuel cell (DUFC) with raw urine as fuel. The molybdenum nickel phosphides on nickel foam (MoNiP/NF) were synthesized using a combined hydrothermal and phosphating method. The honeycomb-like MoNiP/NF catalyst with a Mo/Ni molar ratio of 0.50 (i.e., MoNiP/NF-0.50) showed the highest electrocatalytic activity for urea oxidation among different catalysts. The stacked membraneless DUFC was constructed using the MoNiP/NF-0.50 electrode as anode and a gas diffusion cathode. With the electrode spacing of 5 mm and 6 electrode pairs, the stacked membraneless DUFC had a maximum voltage of 0.55 V and a power density of 0.115 mW cm −2 at the external resistance of 1000 Ω, at which the power output was 5.32 times higher than that in the individual membraneless DUFC. The urea removal reached 65.8% in the cell at the external resistance of 100 Ω within 192 h. The excellent performance of the cell could be attributed to the high activity of the MoNiP/NF-0.50 catalyst, small electrode spacing, and multiple electrode pairs. Our results should provide promising potential for scalable DUFC with efficient urine treatment.