Adverse weather had hampered seabed preparations, but installation is going ahead on schedule, E.on said.
Preparation work started in September and the first load of foundations was delivered in mid-January.
"I'm pleased that our highly skilled team have been able to overcome the poor weather conditions that we've faced over the last few weeks and continue with the construction of the wind farm as planned," said E.on's project development manager, Chris Tomlinson.
Rampion will comprise of 116 MHI-Vestas V112 3.45MW turbines at a site 13km off the UK's south coast, near Brighton.
E.on holds a 50.1% stake in the project following investments from the Green Investment Bank (25%) and Canadian energy firm Enbridge (24.9%).
