Jura and Lewis will receive £887,905 under Big Lottery Fund Scotland's Growing Community Assets programme which encourages community acquisitions.
The Isle of Jura Development Trust will use their £653,225 to redevelop the only convenience store and post office on the island.
The shop, in the centre of Craighouse, the island's main town, was built around 1850 and is a listed building. It was put up for sale last August and with no forthcoming buyers the potential closure of the store prompted the community purchase project.
The Jura Development Fund believe a functioning shop will reduce the need to travel and create new jobs.
John Potts, chairman of the fund, said: "We're delighted to receive the funding to make this project a reality. The grant from Big Lottery Fund Scotland will enable the community to take over ownership of the island's only shop and refurbish it, making it more accessible and giving it a new lease of life"
The Co-Chomunn Na Pairc group on the Isle of Lewis will spend £234,680 to develop and 24-hour access to fuel in the South Lochs area. At the moment the nearest petrol station is over 20 miles away.
John Randall, Chairman of Co-Chomunn na Pairc, said: "A fuel service at Ravenspoint will greatly enhance our facilities."