The story of the Flora Köln is a reflection of the eventful history of the last 150 years. The original building was officially opened on 14th August 1864, with a grand ball, concert and firework display: a palatial conservatory made of cast iron and glass, designed by the Cologne architects Max Nohl and Joseph Felten. The architectural design was inspired by the Crystal Palace in London and by the Jardin d'Hiver in Paris, with Arabian and Moorish style elements as well as Romanesque round arches and hints of the renaissance. The project was financed by patrons from the upper levels of the city’s bourgeoisie, among them the well-known Cologne banker Eduard Baron von Oppenheim. In 1862 a company was founded under the name “Actien-Gesellschaft zur Anlage eines Botanischen Zier- und Lustgartens”. Six months later the Flora KG was set up with the approval of the Prussian King Wilhelm I, and his wife, Queen Augusta, assumed the protectorate of the Flora.

The building is located in the heart of the actual Flora, an extensive, symmetrically-arranged garden, laid out by Peter Joseph Lenné in the so-called "mixed German garden style", and includes elements of the French and the Dutch baroque, the Italian renaissance and the English landscape style. In the 19th century, the park and building were frequently used as exhibition grounds: in 1875 and 1888 horticultural exhibitions were held, in 1889 an industry exhibition and in 1906 the "German Art Exhibition". The park was enlarged between 1912 and 1914 to become the Botanical Gardens, with greenhouses for tropical and subtropical plants and orchids. Both sections were combined in 1920 to form a park covering 28 acres.

The entire gardens - and also the Flora – suffered extensive damage during the 2nd World War. The financial resources required for reconstruction in the former style were lacking and, therefore, a decision was made in favour of a more pragmatic solution: a tiled hip roof replaced the former barrel roof made of glass and the outer towers were provided with small spires. The façade remained largely unchanged.

In 1978-79, the building was completely restored and thus became an attractive banqueting house. Parts of the old constructions were thereby revealed once again – for example, the cast-iron columns in the historic large hall – and as a result, the Flora was given back a reminder of the good old days. As the entire Flora represents an important legacy of the social and horticultural history of Cologne, in July 1980 it was added to the city’s list of protected monuments.

At the beginning of 1988, a start was made on the "restoration" of the gardens which were reopened to the public with a grand festive event in March 1988 - their 125th anniversary – in the new "old" style. In 1995 the ancillary rooms of the Flora were renovated and the catering areas extended to include the Park Salon as well as the Bistro.
In June 2006, the Council of the City of Cologne decided to transfer the operation of the Flora to the municipal subsidiary KölnKongress. Following the first renovation and redevelopment measures, the "Flora Köln" now presents itself with a new logo and the tried and tested service of KölnKongress.

Within the context of the planned general redevelopment, it is planned for the Flora Köln to have a domed roof based on the old model. Following extensive redevelopment measures – as in the Gürzenich Köln – organizers will then be provided with the latest event technology in a historic setting.