Robert Moog constructed his own theremin as early as 1949. Later he described a theremin in the hobbyist magazine Electronics World and offered a kit of parts for the construction of the Electronic World's Theremin, which became very successful.

In 1953 at age 19, Robert Moog founded his first company, R.A. Moog Co., to manufacture theremin kits. During the 1950s, composer and electronic music pioneer Raymond Scott approached Moog, asking him to design circuits for him. Moog later acknowledged Scott as an important influence. Later, in the 1960s, the company was employed to build modular synthesizers based on Moog's designs.

In 1972 Moog changed the company's name to Moog Music. Throughout the 1970s, Moog Music went through various changes of ownership, eventually being bought out by musical instrument manufacturer Norlin. Poor management and marketing led to Moog's departure from his own company in 1977.

In 1978 after leaving his namesake firm, Moog started making electronic musical instruments again with a new company, Big Briar. Their first specialty was theremins, but by 1999 the company expanded to produce a line of analog effects pedals called moogerfoogers. In 1999, Moog partnered with Bomb Factory to co-develop the first digital effects based on Moog technology in the form of plugins for Pro Tools software.

In the late 1980s Moog repaired the original theremin of Clara Rockmore, an accomplishment which he considered a high point of his professional career. He also produced, in collaboration with first wife Shirleigh Moog, Mrs. Rockmore's album, The Art of the Theremin. Dr. Moog was a principal interview subject in the award-winning documentary film, THEREMIN- An Electronic Odyssey, the success of which led to a revival of interest in the theremin. Moog Music went back to its roots and once again began manufacturing theremins. Thousands have been sold to date and are used by both professional and amateur musicians around the globe. In 1996 he published another do-it-yourself theremin guide. Today, Moog Music is the leading manufacturer of performance-quality theremins.

Despite Moog Music's closing in 1993, Robert Moog did not have the rights to market products using his own name throughout the 1990s. Big Briar acquired the rights to use the Moog Music name in 2002 after a legal battle with Don Martin who had previously bought the rights to the name Moog Music. At the same time, Moog designed a new version of the Minimoog called the Minimoog Voyager. The Voyager includes nearly all of the features of the original Model D in addition to numerous modern features.