On 14 June 1990 the international world's fair organization Bureau International des Expositions awarded Expo 2000 to Hanover, beating out Toronto by a 21 to 20 vote. In 1992, the architects Studio Arnaboldi/Cavadini of Locarno won an international design competition for the masterplan of the exhibition grounds. On 12 June that year, a survey conducted by the city council was made public showing only 51.5% of area residents supported hosting the expo.
On 5 May 1994 a new company was created by the government in Bonn, Gesellschaft zur Vorbereitung und Durchführung der Weltausstellung EXPO 2000 in Hannover (EXPO 2000 Hannover GmbH). Headed by chairman Helmut Werner, the company was responsible for the construction and management of the fair.
In 1995 the supervisory board agreed on the concept for the thematics of the fair. Construction finally began on 22 April 1996.
Unlike previous expos, which focused on present advances in science and technology, EXPO 2000 focused more on developing and presenting solutions for the future.
The fair opened to the public on Thursday 1 June 2000 and ran for five months, ending on Tuesday 31 October.
The Expo site was situated on the original 1,000,000 square meters of the Hanover fairground; an additional 600,000 m² was also made available as a newly opened section to the grounds. As a visitor walked in and tickets were taken, looking above to the approximately four-story-high ceiling, a visitor would have noticed the huge circular pods that held large TVs showing animated people greeting the visitors and providing tourist information in different languages. Some ten large McDonald's restaurants were also built, along with restaurants representing several of the exhibitor countries. Small retail locations were also set up to supply Expo merchandise. The United States reversed its decision to take part at a relatively late stage, and the area set aside for the American pavilion was left undeveloped.
40,000,000 visitors were expected at Expo 2000, but only 25,210,000 people came to see the event. This led to a financial deficit of about $600,000,000. With pre-ordered tickets priced at 69 DM, the fair seemed expensive compared to other days out. Commentator Georg Giersberg wrote in the Frankfurter Allgemeine that entrance fees for Germany's 53 main theme parks cost on average less than half the price of the Expo (about 30 DM). Other financial shortfalls came from a lack of corporate sponsorship, since it cost US$4.8 million to be an official product supplier or US$14.5 million to become a world partner.
Part of the failure of the Expo was a lack of clear perception of what to expect at Expo 2000, not helped by a "cerebral" advertising campaign that had failed to explain what the Expo was for. In a 2000 Time article, a Berlin-based marketing firm, Scholz & Friends, stated that "the organizers have failed to convey to the public a clear image of what Expo 2000 is going to be: an entertainment park, a blown-up museum, or a nature reserve." In the same article, Ralf Strobach, secretary of Hanover's Citizens' Initiative for Environment Protection, said that "For a long time, companies were unsure if they would be putting money in an eco-show or a showcase for their latest inventions." Only after the fair was open and clearly not meeting expectations was a new advertising campaign created, aimed at the domestic market with British actor Peter Ustinov and German television star Verona Feldbusch and stressing the fun side of the Expo, under the slogan "Das gibt's nur einmal, es kommt nie wieder" ("This only happens once, it's never coming back").
The German band Kraftwerk created a vocoded speech signature theme, "Expo 2000", which was also developed into a single of the same name. Later, a remix single "Expo Remix" was released. The band was also paid US$190,000 for a five-second jingle, leading Chancellor Gerhard Schröder to state that he "wouldn't have spent so much money".