For the 1925 model year, Nash introduced an entry-level marque named the Ajax. A car of exceptional quality for its price, the Ajax was produced in the newly acquired Mitchell Motor Car Company plant in Racine, Wisconsin. Mitchell was the manufacturer of Mitchell-brand automobiles between 1903-1923.

LaFayette Motors was the producer of a large, powerful, expensive luxury car. The company started in Indianapolis, Indiana, in 1920, and later moved to Milwaukee, Wisconsin. The principal stockholder in LaFayette Motors was Nash Motors Company. Other major stockholders were Charles W. Nash and various of his friends and business associates. The high quality, high priced LaFayette cars did not sell well.

In 1924 Nash absorbed LaFayette Motors of Milwaukee, Wisconsin, and converted its plant to produce Ajax automobiles. The LaFayette name was reintroduced in 1934 as a lower priced companion make to Nash. LaFayette ceased to be an independent marque with the introduction of the 1937 models. From 1937 through 1940, the Nash LaFayette was the lowest priced Nash and was replaced by the new unibody Nash 600 for the 1941 model year.

Before retiring, Charlie Nash chose Kelvinator Corporation head George W. Mason to succeed him. Mason accepted, but placed one condition on the job: Nash would acquire controlling interest in Kelvinator, which at the time was the leading manufacturer of high-end refrigerators and kitchen appliances in the United States. The resulting company, as of January 4, 1937, was known as the Nash-Kelvinator Corporation. Nash as a brand name continued to represent automobiles for Nash-Kelvinator.

In 1938 Nash introduced an optional conditioned air heating/ventilating system, an outcome of the expertise shared between Kelvinator and Nash.

The aerodynamic 1949 Nash "Airflyte" was the first car of an advanced design introduced by the company after the war. Its aerodynamic body shape was developed in a wind tunnel. Nils Wahlberg's theories on reducing an automobile body's drag coefficient resulted in a smooth shape and enclosed front fenders. Wide and low, the automobile featured more interior room than its 1948 predecessor. Due to its enclosed front fenders Nash automobiles had a larger turning radius than most other cars.

Nash-Kelvinator's President George Mason felt Nash had the best chance of reaching a larger market in building small cars. He directed Nash towards the development of the first compact of the post war era, the 1950 Rambler, which was marketed as an up-market, feature-laden convertible. Mason also arranged for the introduction of the Austin-built small Metropolitan from Britain, which was introduced as a 1954 model.

The full-size Nash Airflytes were completely re-designed for 1952, and were promoted as the Golden Airflytes, in honor of Nash Motors' 50th anniversary as an automobile builder (the company now counting the years of the Thomas B. Jeffery Company as part of their own heritage.) "Great Cars Since 1902" became one of the company's advertising slogans. The new Golden Airflytes presented a more modern, squared-off look than did the 1949-1951 models, which were often compared to upside-down bathtubs.

Mason also worked with British car enthusiast Donald Healey to create the Nash Healey in 1951 — the first American sports car built since the depression.