The 37-year-old man, who was working for a contractor, fell to his death inside a tower which was under construction.
The accident happened on Wednesday night during construction at ScottishPower’s 239 mw Kilgallioch wind farm at Barrhill, which is 18 miles north of Newton Stewart.
Police Scotland were called to the site where 96 turbines are being built near the Ayrshire village around 6.45pm on Wednesday night.
Emergency services also attended but the man was pronounced dead at the scene.
A Police Scotland spokeswoman said the site has been closed and that inquiries into the incident are at an early stage.
The Health and Safety Executive has also been notified and police said a report will be sent to the Procurator Fiscal.
A ScottishPower Renewables spokesman said: “SPR can confirm the fatality of a 37-year-old man working for a contractor at Kilgallioch wind farm in South Ayrshire.
“A full investigation is now under way by the police and the HSE. SPR will support and co-operate fully with these investigations. Our thoughts are with the family of the technician involved in the incident.”