The review - led by director general Mark Thompson - followed widespread criticism of the sums paid to BBC executives, particularly in the light of the economic downturn.
The trust has also accepted Mr Thompson's proposal that the pay of the top 20-or-so executives would continue to be frozen for the next three years.
This will also apply to Mr Thompson's salary.
The next 630 senior managers will have a further one-year pay freeze.
The 25% cut to the senior management pay bill will be implemented by 31 July 2013.
The 18% reduction in the total number of senior managers equates to more than 100 posts.
BBC Trust chairman Sir Michael Lyons says he welcomes the management cuts
BBC Trust chairman Sir Michael Lyons said: "Mark Thompson and his team have responded with a comprehensive set of proposals that strike the right balance between ensuring the BBC can attract the best people to do the job, while ensuring maximum value for the licence fee payer.
"Of course I realise this will have implications both for current and future BBC employees. However, it is right that, as a major public service organisation, the BBC shows leadership on this issue during difficult economic times."
Mr Thompson said he and every other senior manager needed to recognise that "we are in a different economic climate, that the media sector labour markets are depressed and that there are significant pressures on public finances".
He added: "A few months ago, we announced our determination to reduce the amount we pay top on-air talent.
"The recommendations we have announced today seek to achieve similar reductions within our senior management community.
"Senior managers will see their total remuneration fall over the period, with the biggest reductions felt by those in the most senior positions."
Conservative MP Mark Pritchard, a member of the Commons all-party media group, said the BBC remained "one of the most secretive publicly-funded organisations outside of the intelligence services".
"This is tinkering with a pay rewards and expenses system within the BBC that actually requires a complete and comprehensive overhaul," he added.
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