The incident happened on Thursday at the 10MW Corkermore wind farm in Donegal in the north west of the country, which is operated by utilities company Energia.
The broken blade section was found 30 metres from the wind turbine, embedded in the ground.
The incident is now under investigation by manufacturer Gamesa in order to find the cause of the incident. Technicians from the company will also carry out precautionary checks on each of the turbines on site.
Energia said that high winds were blowing at the time of the break, but said that "wind speeds are considered to have been within normal operating parameters when the break occurred."
The G80 is designed for high-wind sites and has a cut-out speed of 25m/s. All five of the Gamesa G80 turbines were in operation at the time of the blade break.
The turbine brought itself to a stop automatically and there was no damage to any other turbines or facilities on the site, Energia said.
This is the second incident in a month concerning the G80 turbine, with a fire burning out the nacelle of a turbine on the 74MW Bii Nee Stipa II wind farm in Oaxaca, Mexico on 26 November.