Citroën approached another engineer, Jules Solomon, who had a good reputation in the French automotive industry and had in 1909 built a small car called Le Zipper. André Citroën's mandate was both distinctively demanding and distinctively simple: to produce a completely new design for a 10 hp car that was better equipped, more powerful and less expensive to produce than any competing product at the time.

The result was the Type A, which was announced to the press in March 1919, just four months after the guns fell silent. The first production Type emerged from the factory at the end of May 1919 and in June was displayed in a showroom at number 42 on the Champs-Élysées in Paris, which normally sold Alda cars. Citroën persuaded Alda owner Fernand Charron to lend him the showroom, which is still in use today. Showroom C42 is where the company holds exhibitions and displays its vehicles and concept cars. A few years later, Charron was persuaded to become a major investor in the Citroën business

On July 7, 1919, the first customer took delivery of the new Citroën Type A 10HP. That same year, André Citroën briefly negotiated with General Motors for a proposed sale of Citroën. The deal was nearly done, but GM eventually decided that its management and capital would be overstretched by the takeover. Citroën thus remained independent until 1935.

Citroën produced half-track vehicles for military and off-road use, using the Kegres track system. In the 1920s, the US Army purchased several Citroën Kegres for evaluation followed by a license to produce them. This led to the Army Ordnance Department building a prototype in 1939. In December 1942, it went into production with the M2 half-truck and M3 half-truck versions.

The United States eventually produced over 41,000 vehicles in over 70 versions between 1940 and 1944. After their occupation of France in 1940, the Nazis captured many Citroën half-track vehicles and repurposed them for their own use.

The Eiffel Tower served as a billboard for Citroën from 1925 to 1934 Mr. Citroën was an enthusiastic marketer: he used the Eiffel Tower as the largest advertising sign in the world, as recorded in the Guinness Book of Records. He also sponsored expeditions to Asia with the Cruz Jean, North America with the Cruz Blanche and Africa with the Cruz Noir, demonstrating the potential of motor vehicles equipped with a Kegress track system to cross inhospitable regions. These expeditions transported scientists and journalists.