Work started this month (January 2010) and will phased across different areas of the hotel. The first phase should be completed by April, with all the rooms ready by July 2010.
Sheraton Grand Hotel and Spa Room Picture shows an example of the new rooms being created at the Edinburgh hotel; courtesy of Sheraton.
Ogilvie Construction managing director Phil McEwan said: "We were delighted to win this contract and are committed to helping Sheraton deliver its amazing vision for its Edinburgh hotel.
"Ogilvie has considerable experience in the hotel and leisure sector, having worked on everything from budget accommodation to five-star properties like the Sheraton Grand.
"We have just started work on site and aim to deliver the project with the minimum level of disruption to guests. The plans are very exciting and I'm sure the finished product will be fantastic."
The hotel's general manager, J P Kavanagh, said: "Over the years we have continually invested in the hotel - including the creation of Europe's most advanced city spa, One Spa, in 2001. However, it is time to completely improve and enhance the rooms' product with this sizeable investment in Edinburgh's largest conference hotel.
"As the economy begins to recover, the Sheraton Grand Hotel & Spa will be in an enviable position, poised to leverage our renovated product and offer guests Sheraton's signature brand offerings at one of Scotland's leading hotels.
"We are already starting to see growth in occupancy, particularly in the important corporate market which is very encouraging. We look forward to welcoming both former and new guests as we celebrate our 25th year in the city."
The company says that guest feedback and staff input formed a vital part of the planning process for the refurbishment programme.
The design of the Sheraton Grand's new rooms has been undertaken by MKV Design, a leading interior design company which services the international hospitality sector.
The refurbished rooms will feature mood lighting, designer bathrooms and state of the art technology. A Club floor will also be created on the top floor of the hotel, providing guests with an enhanced level of service and a "hotel within a hotel" concept.
The Sheraton is also creating an imposing Grand Suite - offering spectacular views of the iconic Edinburgh Castle.
Globally, Sheraton Hotels & Resorts has invested $6 billion in a multi-billion global revitalisation effort as part of a three-year global overhaul.
For more information on the Sheraton Grand Hotel & Spa visit www.sheratonedinburgh.co.uk