The Old Forge in Inverie, which lies on the Knoydart Peninsula in Lochaber, is only accessible by an 18-mile (29km) hike over Munros or a seven-mile (11km) journey by boat.
The pub, listed in the Guinness World Records as mainland UK's most remote pub, went up for sale earlier this year for offers over £425,000.
The Old Forge Community Benefit Society, a group of Knoydart residents fundraising to bring the pub under community ownership, had raised £256,035 to buy the property.
But now the group has won a £508,000 cash injection through the Scottish Land Fund (SLF) to support its community buyout.
SLF provides more than £1 million to eight local community groups in the country to help them take ownership of land and buildings that matter to them.
The funding was announced by the Scottish government's land reform minister, Mairi McAllan, during Community Land Week.
She said: "All across Scotland, communities are taking ownership of the land and buildings that matter to them with the support of the Scottish Land Fund.
"I know how hard people will have worked to develop their projects and to achieve this success, and I look forward to seeing the benefits for their communities."
Other projects awarded funding included Port Bannatyne in Argyll and Bute, Canna in the Scottish Highlands, Easter Breich in West Lothian, Carloway Estate Trust in the Western Isles, Bigton Collective Ltd in Shetland, Balquhidder, Lochearnhead and Strathyre Community Trust in Stirling and Inchinnan Development Trust in Renfrewshire.