Direct borohydride fuel cells (DBFCs) exhibit the potential for a wide range of applications due to their high energy and power density; however, the hydrolysis of BH4 − significantly limits the use of DBFCs. In this paper, PdNix-B/carbon nanotubes (PdNix-B/CNTs) (x = 0, 0.3, 0.6, 0.9) composites have been prepared by a chemical reduction method in which PdNix-B nanoparticles of approximately 3.5 nm are grown on the surface of carbon nanotubes. A cell was assembled with PdNix-B/CNTs as the anode catalyst, a polymer fibre membrane (PFM) as a substitute for the Nafion membrane and LaNiO3 as the cathode catalyst. The results show that the Ni element displays an ability to balance the competition between the hydrolysis and oxidation of BH4 −. A peak power density of 105 mW cm−2 (x = 0.9) was achieved at 25 °C. However, the highest fuel efficiency of 69% was achieved at x = 0.3, and the corresponding power density was 87 mW cm−2, which represents the best comprehensive performance of these DBFCs.