The first agreement with BWSC East Anglia will see GDF buy the electricity generated from the 44.2MW Snetterton biomass plant in Norfolk.
The facility, which is due to open in late 2016, will primarily burn straw and generate about 350GWh of energy per year for around 68,000 homes.
Under the other deal with Templeborough Biomass Power Plant, GDF Suez will buy all output from the Templeborough plant in Rotherham, South Yorkshire.
The 39.3MW facility, which is expected to be commissioned in March 2017, will burn waste wood to generate 315GWh of energy per year.
GDF Suez said it will buy the output from both the plants at an index-linked rate, providing a market-reflective price for every kWh of electricity generated.
The company will also purchase all ROC and LEC certificates received by the two plants.
GDF Suez Energy UK head of local portfolio management Paul Roberts said: "These new agreements are the first PPAs we have secured for biomass plants, having previously focused on wind power and energy-from-waste technologies.
"It demonstrates the flexibility of our PPAs, which present an attractive and secure proposition for any type of renewable energy plant."
