A government report recommends that the international terminal be retained for use by domestic rail services after Eurostar's move to St Pancras in 2007.
The study, carried out by Arup, was commissioned by the Department for Transport in March. The consultants even considered the possibility of lifting the tracks in the station and converting the building to residential or retail use.
Announcing the findings of the study, transport secretary Alistair Darling said: "Waterloo International Station is important for passengers. I have agreed that the international platforms should be retained for domestic rail use.
"The Department now has further work to do in order to decide what services will use these platforms and once this is complete, some construction work will be needed on the platforms themselves."
"We welcome the Government's announcement that Waterloo's international terminal should remain in rail hands, benefiting many thousands of domestic commuters using the station," said Paul Charles, Eurostar's communications director.
"Waterloo has been our home for over a decade and, although our move represents a transformation for international rail travel, we are delighted to be giving something back to rail users into and out of London."
The news comes in the same week that Network Rail indicated that it would soon be announcing plans for a major redevelopment of Waterloo station.