The facility in Washington will safeguard hundreds of highly-skilled manufacturing jobs in the North East.
The Derby-headquartered engineering giant's new plant will make more than 2,500 fan and turbine discs a year – essential parts of a plane's engine. It will also make discs for parts for the world's fastest-selling civil aircraft engine, Trent XWB, which goes into Airbus' A350 XWB.
Deputy Prime Minister Nick Clegg and business secretary Vince Cable opened the plant and also announced £45m of joint government and industry funding for three projects led by Rolls-Royce through the Aerospace Technology Institute to develop new technology for low-carbon aircraft engines.
"We should be really proud that the UK is the number one aerospace industry in Europe and a world leader in innovation," Clegg said.
"The highly skilled workers at the new Rolls-Royce factory are leading the charge for innovative technologies that are made in Britain. And the government's investment of £45m alongside industry will help to ensure the UK continues to build and design the planes of the future."
Cable added: "The UK is at the forefront of the global aerospace industry, and investments such as this new factory from Rolls-Royce will help to keep us there.
"The projects that we are funding through our aerospace industrial strategy will ensure that Britain develops the efficient and environmentally friendly aircraft of the future, while keeping highly-skilled manufacturing jobs here in Britain."
The £45m funding will be used for research and development to reduce carbon emissions by using lightweight composite materials to make Rolls-Royce engines.
Research will also focus on changing parts of the engine design to make engines more efficient and reducing the time it takes to manufacture them.
The research will be carried out by a number of partners from across the UK including the University of Birmingham, the Advanced Manufacturing Research Centre in Sheffield, the Advanced Forming Research Centre in Glasgow, the Manufacturing Technology Centre in Coventry and the Universities of Nottingham, Oxford and Sheffield.
The investment is a part of the aerospace industrial strategy, jointly developed by industry and government through the Aerospace Growth Partnership. Funding of £2bn funding has been provided by government and industry to support the strategy.
Gary Elliott, chief executive of the Aerospace Technology Institute (ATI), said: "We are launching three research projects led by Rolls-Royce that will help the UK develop more efficient, technologically sophisticated aircraft engines."