At around 8am, about 20 minutes into the flight to Paris, the pilot saw there was a problem with the instruments and decided to turn around and come back to Skavsta," the airport's chief executive Dot Gade Kulovuori told AFP.
"He first had to circle for a while to burn off some fuel and to show technicians on the ground that the wing flaps and everything were working properly. They were, and he landed safely," she said, adding that she had no further details of the plane's technical difficulties.
All the 173 people including one infant on board had left the plane, she said, adding: "They all seem calm."
Ryanair has sent a plane from London to pick up passengers waiting to fly from Paris to Sweden, and that plane will take the passengers at Skavsta to the French capital, Kulovuori said.
Stockholm Skavsta is Ryanair's main hub in Sweden with the airline servicing almost 50 destinations from the airport.