The Iberdrola-owned company said the blade detached itself from the turbine in the early hours of Friday morning and the Scottish plant automatically switched itself off.
Siemens is currently investigating the cause of the incident while examining the remaining turbines. ScottishPower said it expected Whitelee to be up and running by the end of the week.
No one was hurt or endangered as a result of the incident. However, Whitelee has an extensive network of trails for walking and cycling as part of its multi-million pound visitor centre.
Keith Anderson, Managing Director of ScottishPower Renewables, said: "This type of incident is exceptionally rare and highly unusual.
"However the safety of our people and the public is our first priority. While the investigation into the cause of the incident is ongoing our engineers continue to conduct an internal and external examination of all turbine blades at the windfarm."
Blade failure on turbines is relatively rare. One recent incident is a blade split on a Gamesa 2.5MW turbine at the 50MW Kumeyaay wind plant, owned by Australia’s Infigen Energy, an offshoot of now defunct Babcock & Brown.
In 2008 Vestas was at the centre of a blade failure when a 23 metre blade came off an eight-year-old V47 660 kW machine installed at Windpark Tuitjenhorn in the province of Noord-Holland.
For more see 'Siemens yet to discover reason for blade break'