Energy firm E.On said an initial load of foundations for the Rampion wind farm arrived on site from the Netherlands last week.
Installation will begin in the northwest quadrant of the site between Peacehaven and Worthing, off Sussex.
E.On said the project remained on schedule despite bad weather disrupting preparation work on the seabed.
Thousands of boulders have been moved to make way for the cable route and around each of the turbine positions.
"After almost six years of development it's a really proud moment to finally be installing the first foundations," said development manager Chris Tomlinson.
"These foundations will be piled into the seabed and will act as a base for each of the 140m turbines, which we will start erecting in early 2017."
The Rampion wind farm is the first to be built off the south coast.
The Â£1.3bn construction is eight miles offshore and will be visible from beaches at Brighton and other resorts and the South Downs National Park.
Construction is being managed from Newhaven Port until the wind farm's operations base is completed in 2017.
Foundations are being laid for the first of 116 wind turbines off the south coast.