In 1925, Henningsen presented the Paris Lamp (Danish: Pariserlampen) at the International Exhibition of Modern Decorative and Industrial Arts at Paris. Henningsen won the gold medal for this creation. Lamp consisted of 6 shades and was made of silver. An early model of this lamp sold for £87,500 at auction in 2016.
He is most associated with his design of the PH-lamp series of glare-free, shaded lamps. His lamps used carefully analyzed reflecting and baffling of the light rays from the bulb to achieve illumination that was not harsh and glaring but shed warm, soft light. His light fixtures were manufactured by Danish lighting manufacturer Louis Poulsen, a company with which Henningsen would build a lifelong working relationship. His novel works of Danish modern designs are featured in many museums.He entered into with the architect Kay Fisker in 1919. From 1920, Poul Henningsen freelanced as an architect and designer.
In 1920, Henningsen created the Slotsholm Lamp (Danish: Slotsholmslygte) which was installed between the Højbro and Holmens bridges along the Christiansborg Slotsplads canal in central Copenhagen. The prototype lamp consisted a lantern with a large top plate shade on a thin post. Henningsen designed the lamp to differ from the traditional design of gas light fixtures. In a column of Politiken in October 1921 where he wrote about the lamp, he criticized the habitual thinking and conservatism that he witnessed in the field of street lighting and emphasized that electric lights, like his Slotsholm Lamp, must have completely different and unfamiliar appearance than gas lighting. Only seven Slotsholm Lamps were ever created. The failure of the lamps to gain popularity may be due to the manufacturer, Copenhagen Lighting Service, removing some components of the lamp because they caused the light to glare. This was an issue that Poul Henningsen would later solve and the glare-free design feature would become a signature characteristic of his work.
The Paris Lamp
in 1921, he began his journalistic career when hired by Politiken to cover architecture. His writing emphasized the relationship between societal problems and architecture and the effects of Copenhagen's transformation into an urban metropolis. His journalism often focused on what he perceived to be the short-term thinking of municipal authorities' urban planning.