He worked in the École Nationale des Ponts et Chaussées in Paris, France where he designed several bridges until the First World War intervened.

Freyssinet's proposal was for three reinforced concrete truss spans, and was significantly less expensive than the standard masonry arch design.

Eugène achieved a significant breakthrough in thin-shell structures with the design of two huge and celebrated airship hangars at Villeneuve-Orly Airport in 1923.

[1] Also in 1919 his Pont De La Liberation in Villeneuve-sur-Lot was completed which was the largest single span in the world at 96.25 metres.

Freyssinet's key contribution was to recognise that only high-strength prestressing wire could counteract the effects of creep and relaxation, and to develop anchorages and other technology which made the system flexible enough to be applied to many different types of structures.

Many of Freyssinet's designs were new and elaborate for his time—some of them so much so that they were never built, such as the Phare du Monde, a 2,300 foot tower planned for the 1937 World Fair in Paris.