In the present review, we highlight the important results provided by literature studies, especially those from the last ten years, dealing with sonochemistry and ultrasound-assisted hydrogen generation techniques, and discuss the possibility of biomass valorisation as lignocellulosic and different wastes into high-value products and hydrogen production by photocatalytic and sonophotocatalytic means from a mechanistic and technological perspective with comparison to conventional techniques and clarifying the future attitudes. Various aspects of this field have been addressed in the sub-sections. The first section discusses the principle of ultrasonic technique from the principle to its application for green energy with an extensive discussion regarding the complementary impacts of cavitation events and ultrasonic power.