Mesa/Boogie (also known as Mesa Engineering) is an American company in Petaluma, California, that manufactures amplifiers and other accessories for guitars and basses. It has been in operation since 1969.

Mesa was started by Randall Smith as a small repair shop which modified Fender amplifiers, particularly the diminutive Fender Princeton. Smith's modifications gave the small amps much more input gain, making them much louder as well as creating a high-gain, distorted guitar tone. Prominent early customers included Carlos Santana and Keith Richards of The Rolling Stones. Exposure from these top players helped to establish Mesa/Boogie's position on the market, and it is frequently referred to as the first manufacturer of boutique amplifiers.

Subsequent design revisions to Mesa's early amps lead to the Mark Series, which popularized modern, high-gain circuits, while the 1990s saw the introduction of Mesa's flagship Rectifier amps, the success of which made the brand a staple of modern rock tone. In 2021, Mesa/Boogie was acquired by Gibson.