The Trust ran a service review of the 24/7 BBC News channel and the BBC Parliament network, which found that coverage on both channels was "high quality and provides good value for money".
However, the Trust warned that the channel's "content and style distinctive" must be protected in the BBC's cost-cutting programme, which was initiated following the tough new licence fee deal agreed with the government in 2010.
A variety of different austerity measures have been proposed by the BBC towards the aim of saving around £670m a year by 2016/17, including the elimination of BBC Two's daytime budget and a small reduction in scope of BBC News.
The Trust's review found that the BBC News Channel has reached record levels, with 19.9% of UK adults watching it during 2010/11, up from 11.5% in 2006/7.
It revealed that licence fee payers value the channel for its extensive coverage on subjects such as the economy, politics, health and education.
The Trust called on the News Channel to "continue to improve and innovate", as well as remain "distinctive in an increasingly crowded marketplace for news".
It accepted that the channel must play its part in delivering savings for the BBC, but urged management "not to let any changes detract from the range and depth of stories covered".
The Trust also noted that audiences consider BBC Parliament's live coverage from the Commons to be "unique", and also value the opportunity to see government proceedings first hand with analysis.
BBC Parliament is attracting record audiences, said the Trust, attracting more than 1% of viewers for the first time last year. But it ordered the channel to ensure on-screen contextual information "better meets the needs of viewers".
It also endorsed a BBC plan to introduce easier links to other BBC services on BBC Parliament in order to help people more easily find related information.
"It is clear that News Channel and BBC Parliament users see these services as distinctive, offering coverage and perspectives they cannot find elsewhere. It is also encouraging that these services are so consistently providing value for money for licence fee payers," said BBC Trustee David Liddiment, who led the review.
"The past year has seen some hugely significant news stories - from the summer riots and royal wedding at home, to the Japanese earthquake and Arab Spring uprisings abroad - and audiences tell us that for big national stories the News Channel is their 'go-to' service.
"Despite this strong performance the News Channel must keep seeking new ways to improve and innovate. There is no doubt that the marketplace for news is becoming increasingly crowded, so it is vital that the channel uses its resources wisely and maintains its distinctiveness and quality, to ensure it continues to deliver for licence fee payers."
Yesterday, the Trust announced that party political broadcasts around key events such as the Budget will be axed on the BBC in favour of a new system involving "seasonal" spots designed to increase flexibility.