Budget airline Ryanair is to build a second maintenance hangar at Prestwick Airport, creating up to 200 new jobs.
The £8m investment, supported by £1.5m from the Scottish government, will see both facilities service Ryanair's fleet of more than 200 aircraft.
The airline also said that it would run three new routes from Edinburgh Airport to Faro, Paris and Marrakech from May.
Ryanair said there would be increased frequency on 16 other routes from Edinburgh and Prestwick this summer.
First Minister Alex Salmond, who was at Prestwick for the announcement, said: "Ryanair makes a substantial contribution to Scotland's economy through its engineering facilities and encouraging tourism and business traffic via its Glasgow Prestwick, Aberdeen and Edinburgh flights.
"The announcement of investment at Prestwick and new routes from Edinburgh supports this government's ambition to increase sustainable economic growth by attracting inward investment and creating quality new jobs."
The Scottish government is supporting the project, through Scottish Enterprise, with the offer of £890,000 in Regional Selective Assistance and £640,000 in training grants.
Ryanair chief executive Michael O'Leary said: "Ryanair's new maintenance hangar at Glasgow Prestwick Airport will create 200 new engineering jobs, in addition to the 2,200 local jobs which have already been created and sustained in Ayrshire as a direct result of Ryanair's base and our existing hangar facility at Glasgow Prestwick.
"Ryanair's successful growth in Scotland is possible thanks to our on-going partnership with the Scottish government and Scottish Enterprise, who have repeatedly supported our vision for many more low fare flights to/from Scotland."