The trees will be planted at the park over the next three winters
A Hampshire nursery will provide the trees to be planted in the 250 acre Olympic Park in east London.
About 2,000 semi-mature are earmarked for the Stratford site and will be planted over the next three winters.
John Armitt, Olympic Delivery Authority chairman, said the site would be the largest urban park to be built in the UK for more than a century.
The trees include willow and alder varieties in riverside settings to help withstand flooding.
Mr Armitt said: "Seeing 2000 semi-mature trees lined up ready to start being planted in the Olympic Park gives you a real sense of the green setting being created for the games themselves and the transformation of this part of London in legacy."
The trees will come from Hilliers Nurseries, Hampshire. Hilliers has worked on projects such as the 1951 Festival of Britain, the Manchester Commonwealth Games stadium and the Millennium Dome.