Mr Hutton, 45, was assistant editor of the Guardian until his appointment yesterday, and is to take up his duties immediately.
The Observer, which has been losing both money and readers, was bought by the the Scott Trust, owners of the Guardian Media Group, from Tiny Rowland's Lonrho for pounds 27m in 1993.
Hugo Young, the trust's chairman, said: "Will Hutton is a brilliant journalist and a significant thinker. We believe that, under an inspirational editor, the Observer will make great strides."
Yesterday's developments marked a further rise in the influence of Alan Rusbridger, editor of the Guardian, who will assist Mr Hutton in the management of the Observer.
Peter Preston, former editor of the Guardian and until yesterday editor in chief of both titles, will now be left with a non-executive position as editorial director of the Guardian Media Group, and a Scott trustee.
"This clearly is a setback for Peter," one senior journalist at the Guardian said. "But this is the price to be paid for having appointed two editors who failed to turn the newspaper around." Mr Jaspan was preceded in the job by Jonathan Fenby.
The Guardian Media Group denied there was any intention of turning the two newspapers into a 7-day operation, by effectively merging the titles. The two titles have already announced job cuts, but there may be additional redundancies following Mr Hutton's arrival. It is understood that Mr Jaspan's deputy, John Price, has already resigned. Mr Hutton's deputy will be Paul Webster, formerly the home news editor of the Guardian.
In a statement yesterday, Mr Hutton said: "My aim is to accelerate the pace at which the title recovers its prestige and honoured place in British national life."Reuse content