The development will include a hotel, offices and retail space, the BBC has reported.
The site in the city centre has been lying empty for several years due to a long-running planning battle, as well as the recession.
Original plans for the project included a 17-story hotel next to Haymarket Station, but this was scaled down after local protests.
The build has full planning permission and has the potential to create 3,500 jobs.
Work is expected to begin this summer after construction company Interserve came on board with landowners Tiger Developments.
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Interserve will invest an initial £10.5m in the project, while the construction contract is for £150m.
Proposals for the site will see the creation of new shops, office blocks, cafés, bars and restaurants as well as 165 serviced apartments.
Tesco is also believed to have signed up, while food chains Prezzo and Pret A Manger have committed for the second phase of the development.
Adrian Ringrose,Chief Executive of Interserve, said: "Edinburgh's Haymarket site remains one of the best city centre development schemes to be found anywhere in the UK.
"It will provide a strategic gateway for the city centre, linking seamlessly with one of Scotland's busiest railway stations as well as being adjacent to the city's new tram network. The proposals for a mix of leisure, retail and office space, linked by open public spaces, will act as a catalyst to regenerate the commercial heart of the area as well as create jobs."
Simon Fox, Development Director with Tiger Developments, added: "Throughout the planning process we have worked hard to develop our proposals in line with the needs of the city and the local community.
"Our team has devoted a significant amount of time and energy so far in designing a scheme which now represents the best solution for this challenging site."
(JP/CD)
