The company that became Heathkit grew out of the E.B. Heath Aerial Vehicle Co, established in Chicago in 1913. Back then, Edward Heath was a budding aviator and airplane designer, and the company he founded sold airplane parts such as radiators and wheels. After building and testing several models, with names like the Feather, Favorite, and Tomboy, in 1926 Heath constructed the single-passenger, open-cockpit Parasol, which had a wingspan of 25 feet and was powered by a 25 hp motorcycle engine. Early versions of the plane sold for just $595, but many more aviation enthusiasts bought the blueprints for just $5.

Tragically, Heath was killed in a test flight in 1931, and in 1935 his bankrupt airplane-parts company was purchased by Howard Anthony, who had been a Heath customer. During World War II, the Heath Company, as it was now known, supplied the military with airplane parts, including radios. After the war, Anthony purchased a large lot of five-inch cathode ray tubes, which he used as the key ingredient in a build-it-yourself oscilloscope kit (model O-1), which sold for under $50. The kits caught on and soon Heath was producing vacuum tube volt meters, condenser checkers, and other electronics-testing instruments. Each kit was accompanied by a detailed manual, with exploded diagrams and step-by-step instructions designed to make Heath products accessible to beginners.

In 1954, Howard, too, was killed in an airplane accident, prompting the sale of the company in 1955 to Daystrom. Soon, the HeathKit line expanded to include home-electronics equipment such as amplifiers, tuners, and speakers, as well as Ham radios. In 1978, it even released a computer kit, the Heathkit H8.