The budget airline has been the only firm to operate passenger flights out of Prestwick since Whizz Air moved to Glasgow at the start of last year.
Ryanair last month announced some services were moving to Glasgow, prompting fears for the future of the Ayrshire airport, but announcing its 2015 summer schedule today chief executive Michael O'Leary said the airline will continue to fly to 16 destinations from Prestwick.
Three aircraft will be based at Prestwick, completing 44 weekly return flights and maintaining around 500 jobs, Ryanair said.
Nine new routes out of Glasgow Airport to destinations including London Stansted, Dublin, Warsaw in Poland and Carcassonne in France have also been announced.
Mr O'Leary said: "Ryanair is pleased to be the first airline in Scotland to launch its 2015 summer schedule, with nine new Glasgow International routes to Bydgoszcz (Poland), Carcassonne, Chania (Crete), Derry, Dublin, London Stansted, Riga (Latvia), Warsaw and Wroclaw (Poland) and just as important 16 Glasgow Prestwick routes, which will deliver 1.35 million customers per annum to and from Glasgow."
The Scottish Government took Prestwick Airport into public hands late last year when its former owner Infratil earmarked it for closure. At the time, it was said the airport supports 1,400 local jobs, is worth £60 million to the Scottish economy and was considered too important to close by ministers.
When announcing its 2014 winter schedule in July, Ryanair said it remained committed to the Ayrshire airport, where it has an engineering base, and was in discussions with the Scottish Government to ''explore growth opportunities''.
The company also unveiled an extended schedule at Edinburgh Airport from next year with a new route to London Stansted and more frequent flights to Barcelona in Spain and the Italian cities of Pisa and Rome among a total of 32 destinations.
Some of the flights will cater for Ryanair's new ''business class'' service, which allows flexibility on ticket changes, 20kg (44lbs) of checked-in bag allowance, fast-track airport security at selected airports, priority boarding and premium seats.