The planes will be built in Lancashire
Ministers have welcomed the signing of a £3bn contract for 40 Typhoon jets as "excellent news" for the armed forces and the defence industry.
The first of the new aircraft, part of the Eurofighter defence programme, are expected to enter service in 2013.
About £900m has been knocked off the cost of the contract after heated negotiations between the UK and its partners Germany, Italy and Spain.
Unions said the deal would protect jobs in Lancashire and Bristol.
The UK has been seeking greater value for money from the latest phase of the Eurofighter project as constraints on its defence budget increase.
On Friday, the four partners - who launched the Eurofighter programme in 1988 - agreed to buy a total 112 combat jets between them in a deal worth £7.7bn.
The UK has said it will order 40 - 24 of those to replace jets previously sold to Saudi Arabia. They will operate from bases in Lincolnshire and Fife.
Negotiations over the contract have been tense with sources suggesting the UK was determined to bear down on costs while its partners were worried about securing the future of 100,000 jobs.
The Ministry of Defence said the agreement was a major milestone in the Typhoon programme, a key element of European defence co-operation.
"This is excellent news for both our armed forces and UK industry," said Quentin Davies, minister for defence equipment and support.
"The contracts have also enabled partner nations to programme significant savings. For the UK, this is of the order of £900m."
'Vote of confidence'
Manufacturers of the jet fighter had warned of thousands of job losses if no agreement was reached.
Unions said the deal would safeguard jobs across the UK, particularly in Lancashire where the plane will be built and in Bristol where its engines will be made.
"After many months of negotiations this announcement on the Typhoon Tranche 3 is great news for the workers and for UK manufacturing," said Bernie Hamilton, from the Unite union.
"This order is a vote of confidence in the skills of UK defence workers."
Under the original agreement, the four countries were to split 620 jets between them in three separate batches. The latest agreement means 559 will either have been delivered or be in production.
The final batch has been divided into two tranches, fuelling speculation that it may be axed - although governments have always denied this.
The global recession is forcing all countries to reconsider their defence budgets and with an estimated cost per plane of £100m, the Typhoon programme has come under particular scrutiny.
The Royal Air Force (RAF) took delivery of its first quota of Eurofighter Typhoon jets in 2003.
Critics say it is an outdated Cold War weapon but the RAF says the upgrade means the fighter will be able to operate more effectively in Iraq and Afghanistan.