The green energy deal between Ontario and the South Korean manufacturer was signed in 2010 but has been subject to a number of revisions since. The contract has been cut from 2.5GW to 1.369GW.
In May, Ontario dropped its feed-in tariff programme and made changes to its local content regulations for wind farms following a World Trade Organisation (WTO) ruling that they contravened international trade law.
Under the terms of the revised deal, Ontario will now buy C$6 billion worth of electricity from Samsung, a cut of C$3.7 billion.
In 2011 the Ontario government slashed C$327 million from a C$437 subsidy towards building factories to make turbine tower and blades.
Samsung has also cut its original commitment to invest $7 billion in new manufacturing plants and renewable energy projects in the province to C$5 billion.