The MarramWind and CampionWind projects, located off the east and north-east coasts of Scotland, are expected to have capacities of 3GW and 2GW respectively.
They will generate enough electricity to power up to six million homes.
The agreements were signed following successful bids in Crown Estate Scotland’s ScotWind offshore wind leasing round.
Charlie Jordan, ScottishPower’s Offshore Wind Director for the UK and Ireland said: “Offshore wind is exactly what’s needed to get more clean, green homegrown electricity on to the grid, so we can reduce our dependency on gas and reach net zero.
“The signing of our ScotWind option agreements also gives us the green light to push on with our ambitions to deliver jobs and investment for local people, businesses and the supply chain across the country – creating a new global industry from right here in Scotland. It’s a really exciting time.”