Next year’s race will be staged at an alternative British venue before the 2016 event takes place at the newly built track near Ebbw Vale.
Spanish giant FCC and local civil engineer Alun Griffiths (Contractors) were due to start on site last year but the project has been delayed by planning wrangles.
Michael Carrick, Chief Executive of the Circuit of Wales, described the deal as a “significant landmark in the development” of the project.
He said: “MotoGP is the pinnacle of global motorcycle racing and expectations within the series and of its millions of fans worldwide are for a truly world class event at iconic and state-of-the art venues.
“We look forward to meeting those expectations when we welcome MotoGP to Wales from 2016.”
The Circuit of Wales will be a purpose-built hub for the British motorsport industry around a state-of-the art track.
The first phase of the development will be the construction of an international specification motor racing circuit and world championship facilities, hotel, commercial and retail complexes.
The facility is designed to host international motorsport events and will be a centre for motorsport-related industries.
Plans include a 3.5-mile track that takes advantage of the natural flow of the unique topography of the area, an indoor academy training facility, motocross, trials and enduro venues, an international kart circuit and driver training facilities as well as a variety of leisure and cultural amenities.