It brings the total it has ordered to 210
They will be delivered over the next four years.
The model was grounded last year after 346 people died in two fatal crashes but the plane has since been approved by the FAA.
Some of the new fleet will take to the skies in early 2021, with Ryanair intending to use them for European flights.
The company claims the planes use 16% less fuel, releases 40% less emissions and seats eight extra people.
