Helicopter manufacturer AgustaWestland awarded £570m contract by the Ministry of Defence (MoD)
The Yeovil-based firm's five-year contract is to support and maintain 70 Westland-built Merlin helicopters, operated by the RAF and Royal Navy.
The town's Lib Dem MP David Laws said the order would safeguard up to 1,000 jobs, most of them in Somerset and at RNAS Culdrose in Cornwall.
He said it was "excellent news" for the town and the armed forces.
He added: "This contract will ensure that the Merlin helicopters continue to be well supported in their deployments - both within Afghanistan and on other operations throughout the world.
"The jobs secured with this contract will also be hugely beneficial to our local economy - as much of the work on these helicopters will be assigned to Westland's factory in Yeovil."
BBC News - Yeovil-based AgustaWestland given £570m MoD deal