The 45 megawatt Ardchonnel windfarm would have been one of the largest in Argyll had it been allowed on the estate of Sir Jamie McGrigor.
However, councillors on Argyll and Bute Council's planning committee unanimously refused to grant the project permission yesterday, in line with recommendations from their officials.
Developers RWE Innogy now have three months in which they can lodge an appeal.
The Ardchonnel project would see 15 turbines, each 364ft tall, erected on the hills above Loch Awe, generating enough electricity to power 40% of the homes in Argyll and Bute.
The proposal proved unpopular among many of Sir Jamie's constituents, dozens of whom lodged formal objections claiming it would ruin the skyline and wreck the local tourist trade.
Sir Jamie, 64, an Eton-educated baronet who has been a Highland and Islands Tory list MSP since 1999, struck a deal with German energy giant RWE to develop Ardchonnel in 2011.
According to their agreement, he would receive £7,000 a year "base rent" for each megawatt of installed capacity, or up to £315,000, plus extra if the windfarm performed very well.
Index-linked over the 25-year life of the turbines, the site, which is currently used to graze sheep, should have generated over £8m.
Sir Jamie argues the windfarm would bring jobs.
However a planning officer report presented to yesterday's meeting in Ardrishaig said Ardchonnel was inconsistent with the local development plan "due to its adverse landscape, visual, and cumulative impact on the landscape setting of Loch Awe" and recommended refusal.
Sir Jamie declined to comment. RWE Innogy UK said they were obviously disappointed. They would consider their options before deciding how to proceed.