Already after the opening of the Fehmarnsund Bridge and the Puttgarden-Rødby ferry route in 1963 – the so-called “Vogelfluglinie”, or “Flying Bird Line” – people were beginning to consider how road and rail traffic could be made more efficient between Scandinavia, Germany and the rest of Europe. However, the project only became a feasible reality in 1991, when Denmark and Sweden planned the construction of the Øresund Fixed Link. In light of this, the two governments saw a Fehmarnbelt Fixed Link as a goal to be pursued. In 1992, Germany and Denmark agreed on comprehensive preliminary investigations of the Fehmarnbelt Fixed Link to be prepared.

From 1995 to 1999, a series of investigations into the technical and financial options, socioeconomic and regional effects, overall economic evaluations, as well as traffic prognoses and environmental effects of a fixed link across the Fehmarnbelt were carried out. To jumpstart interest by private investors in financing shares, a fact-finding process was held in 2001/2002 based on these investigations.

From 2002 to 2005, additional investigations highlighted the overall economic advantages, regional effects, traffic development and financing models of the project. In June 2005, based on the results of these investigations, the German and Danish Ministers of Transport agreed that a cable-stayed bridge would be the preferred technical solution and that an immersed tunnel would be the preferred alternative.

In the years 2005 and 2006, an environmental consultation process was carried out, in which government agencies, interested associations and the public commented on the environmental aspects already examined.

June 2007 saw a formal declaration of intent by the Ministers of Transport of Denmark and Germany, which allowed for the draft of a legally binding state treaty between the two countries concerning the layout, construction and operation of the Fehmarnbelt Fixed Link.

On 3 September 2008, the Ministers of Transport of Denmark and Germany signed the state treaty on the Fehmarnbelt Fixed Link. It provides for a two-track rail connection and a four-lane motorway between Puttgarden and Rødby. The preferred technical solution is a cable-stayed bridge, with the preferred alternative being an immersed tunnel.

On 26 March 2009, the Folketing, the Danish Parliament, approved a planning law for the planning of the fixed coast-to-coast link and the appertaining hinterland infrastructure in Denmark with a large majority, thereby also adopting the 3 September 2008 state treaty. The Danish planning law enables comprehensive preliminary investigations of such matters as the environment, maritime safety and geotechnology for the coast-to-coast link, as well as for the hinterland infrastructure. After planning has been completed, it is anticipated that the Folketing will be presented with a draft construction law in the year 2012.

In Germany, the law ratifying the state treaty was accepted by the Bundestag on 18 June 2009. On 10 July 2009, the Bundesrat also passed it, and the law took effect on 24 July 2009.