•Ultrasound-assisted extraction using clean, green solvents.•Mechanism of ultrasound-assisted extraction.•Design and development of ultrasound-assisted extraction systems. The objective of this review is to discuss the ultrasound-assisted extraction (UAE) of various compounds using clean, green solvents. We also outline fundamental mechanisms and factors associated with the design and the development of clean, green UAE systems. Growing consumer demands for greener alternatives and natural ingredients that do not involve toxic chemicals and the environmental and health risk associated with the use of chemical solvents have attracted the interest of industries to sustainable, non-toxic routes of extraction. UAE can benefit the chemical industry in multiple ways: •enhancing extraction yield;•enhancing aqueous extraction processes without using solvents;•providing the opportunity to use alternative clean and/or green solvents by improving their extraction performance; and,•enhancing extraction of heat-sensitive components under conditions that would otherwise have low or unacceptable yields.