Ultrasound waves generate and enlarge gas cavities in an aqueous solution by compression and rarefaction cycles. When cavities have grown to a certain size, they become unstable and collapse under external pressure. This process leads to a number of effects such as standing waves, microjetting, localized temperature increases, and so on, which can have a positive effect on electrochemical and chemical systems. In this chapter, research studies concerning electroless nickel (Ni) deposition by ultrasound are reviewed. The main benefits of using ultrasound-assisted electroless Ni deposition include (1) increased rate of deposition, (2) modification of coating morphology, (3) modification of coating composition, (4) dispersion of particles for composite deposition and formation of core-shell particles, and (5) improved coating uniformity on complex structures.