Mr Emmott, 36, its business editor, will succeed Rupert Pennant-Rea - who is moving to the Bank of England as deputy governor - on 26 March.
The appointment represents continuity, Mr Emmott having spent his career at the magazine. It also fulfils an Economist tradition to appoint editors under 40.
Mr Emmott was chosen over the Economist's deputy editor, Nico Colchester, 47, from a shortlist of two. The final decision was made yesterday after both were interviewed by the board. The chairman Sir John Harvey-Jones said that it was 'a close contest'. In an apparent reference to Mr Emmott's youth, he added: 'Our editors tend to last a long time: we tried to take a fairly long view.'
Mr Emmott said: 'I will be keeping the paper resolutely upmarket at a time when other publications are tending to move downmarket.'
He refused to be drawn on planned changes, but said that he would not dismiss staff.
The Economist, which is 150 years old in September, has just passed the 500,000 circulation mark. Sir John said: 'The paper is still growing profitably. We wouldn't want major changes.'
Mr Emmott, who is married and owns homes in Covent Garden and Wiltshire, joined the Economist at 24 after completing a Philosophy, Politics and Economics degree (PPE) at Magdalen College, Oxford, and failing to complete a doctorate.
He started his career as Brussels correspondent, became deputy economics writer in 1982, was posted to Tokyo the following year and appointed financial editor in 1986. Three years later he became the business editor.Reuse content