Associated British Ports (ABP) used cranes to lift the structure, known as a whale, from Town Quay in Southampton last year after it had spent decades partially submerged.
The unveiling of a plaque at its new home outside Solent Gateway at Marchwood, Hampshire, was carried out by the Lord-Lieutenant for the county, Nigel Atkinson, with the local MP, local council leaders and veterans in attendance.
Mulberry Harbours, as they were known, were built in the UK and used overseas to help transfer Allied troops and equipment as they began the liberation of France.
Port director Richard Parkinson said: "The Mulberry Harbour was a brilliant piece of British engineering in the Second World War to create the harbour that enabled Operation Overlord and the D-Day landings.
"It was absolutely a battle-winning, innovative British engineering invention."
The whale is one of only two known surviving examples in England that are not submerged.
The Mulberry harbours solved the problem of needing deepwater jetties and a harbour to provide the invasion force with the necessary reinforcements and supplies, and were to be used until major French ports could be captured and brought back into use after repair of the inevitable sabotage by German defenders. Composed of floating but sinkable breakwaters, floating pontoons, piers and floating roadways, this innovative and technically difficult system was being used for the first time.
The Mulberry B harbour at Gold Beach was used for ten months after D-Day, while over two million men, four million tons of supplies and half a million vehicles were landed before it was fully decommissioned. The partially completed Mulberry A harbour at Omaha Beach was damaged on 19 June by a violent storm that arrived from the northeast before the pontoons were securely anchored.
