A Memorandum of Understanding was signed between the Port of London Authority and Crossrail at the end of September, to confirm the commitment to use barges and ships along the river to move the materials.
Using boats instead of lorries to transfer five million tonnes of material will save half a million lorry journeys on Europes largest construction project.
Mayor of London, Boris Johnson said: Moving five million tonnes of earth excavated from the centre of London requires a solution of Herculean proportions. Using the barges rather than the roads is a supremely brilliant plan and it brings joy to my heart to see them make their way up and down the Thames.
Over the course of the Crossrail project, a total of 7.3 million cubic metres of material will be excavated, which is enough to cover the whole of Hyde Park and Kensington Gardens with a three metre thick layer.
Transport Minister Rt Hon Sadiq Khan MP said: This is a welcome announcement, which underlines the green credentials the Government is keen to see applied to this huge project, while reducing disruption to Londons busy streets.
The landscaping projects using the earth include creating a nature reserve for the Royal Society for the Protection of Birds at Wallasea Island in Essex, creating one of the largest wetland nature reserves in Europe for 50 years.