He was born in the Belgian city of Dendermonde, near Ghent. He came to London as a waiter from Belgium sometime before 1849 and became a naturalized English citizen in 1853 and eventually became Lord Mayor of London.
He was knighted on 4 December 1888.
He founded the 400-room Royal Hotel, later to be called the De Keyser’s Royal Hotel, and personally ran it from 1856 to 1887. The De Keyser’s Royal Hotel had approximately 400 rooms and was mostly used by foreigners visiting London, including Americans, Dutch, French and Belgians. (De Keyser himself could speak six languages.) The hotel was very exclusive and initially every guest had to be introduced personally or by letter before they could secure accommodation. It depended almost entirely on this clientele for its success, but was also used for large banquets among City companies. It was taken over by the RAF in 1916.
In 1920, Lord Leverhulme leased the site to build the London headquarters of his soap manufacturing company Lever Brothers, which became Unilever in 1930. Construction did not commence until 1929.
The building design and construction is thought to be a collaboration between James Lomax-Simpson, a member of the Unilever Board, and John James Burnet and Thomas S. Tait, partners in the firm of Sir John Burnet and Partners. However, there is some uncertainty over the credit for the design; a note by Simpson claims exclusive credit, suggesting that Burnet and Tait only approved the final design. Burnet and Tait exhibited the design as a joint work with Simpson at the Royal Academy, and the drawings held at the City of London Record Office are signed by Burnet and Tait alone. John James Burnet, although active in this project, was retiring around this time due to ill health, and Tait, a leading practitioner of modern architecture, worked on aspects of the building design. The main contractor for the construction of the building was Holland, Hannen and Cubitts
The most striking aspect of the building is its enormous curving frontage along the Victoria Embankment, with its giant Ionic columns between the fourth and sixth floors.
The heavily rusticated ground floor is windowless to reduce traffic noise inside the building.
The corners are marked by entrances surmounted by large plinths on which are placed sculptures of human figures restraining horses – called Controlled Energy by Sir William Reid Dick.
Merman and mermaid figures are by Gilbert Ledward who was also responsible for the guards memorial.
The original lift cars were lined with art deco pewter panels designed by Eric Gill.
A refurbishment of 1977-83 saw the addition of parapet figures by Nicholas Munro and a new north entrance lobby in a Neo Art Deco style, by Theo Crosby of Pentagram. The building has been extended along Tudor Street.
In 2004, the firm Kohn Pederson Fox Associates began renovation work in consultation with English Heritage and the City of London to make alterations to the interior work space. As part of the renovations, original fittings were retained or re-used, such as parquet flooring and Eric Gill’s pewter lift car panels, but Crosby’s distinctive and historically-important additions were removed.
A roof garden was created on top of the building.