The Kensington Gardens pavilion, designed by Danish artist Ólafur Elíasson with Norwegian architect Kjetil Thorsen, of Snøhetta, could not be completed in time for the start of the gallery's summer season.
A temporary structure, designed by Zaha Hadid and Patrick Schumacher, opened on the site on 11 July (Zaha's Serpentine Pavilion unveiled), and will now be replaced by the Elíasson/Thorsen design.
This year's pavilion has had an eventful history, with German architect/engineer Frei Otto originally pencilled in to design the building.
However, the RIBA Gold Medal-winner's proposal was postponed until 2008 after it emerged that Otto would need more time to develop it (Otto off Serpentine)
Elíasson and Thorsen were then brought on board, and after an initial hiccup where the wrong fee was enclosed with the planning application, the pair then found they were unable to complete the building in time.
Now finished, Elíasson and Thorsen's timber-clad building resembles a spinning top, with a wide spiralling ramp on the exterior.
The pavilion will act as a 'laboratory' every Friday, with artists, architects, academics and scientists engaging in a series of public 'experiments'.
The Serpentine Pavilion is an annual commission, given to architects who have not completed a building in the UK.
Previous designers include Toyo Ito with Arup (2001), Oscar Niemeyer (2003), and Rem Koolhaas and Cecil Balmond with Arup (2006).
This year's pavilion will be open to the public until 5 November.