Regional authorities signed off on the concession to use the "maritime public domain" consents under environmental law and exemptions concerning certain protected species for Dieppe-Le Tréport, which was tendered in 2014.
Similar authorisations were also issued to state utility RTE for the grid connection.
"It is a major milestone," said Christophe Leblanc, development director at project company Eoliennes en Mer Dieppe-Le Tréport (EMDT), owned by Engie, EDPR, Sumitomo Corporation and the state-owned investment company Caisse des Dépôts.
EMDT can now finalise the project design and launch tenders to select its main suppliers, apart from Siemens Gamesa Renewable Energy (SGRE), which is already committed to supplying 62 8MW turbines, to be built at Le Havre.
"The next 18 months will be mainly focused on building the supply chain," Leblanc explained.
They will also be working on the schedule to comply with the tender terms. This means starting offshore installation in 2022, for full commissioning in 2023.
Nevertheless, it is almost certain that the rulings will now face lengthy legal challenges, as has happened with France's other offshore projects: Courseulles-sur-Mer, Fécamp and St-Nazaire, authorised in 2016; St-Brieuc, in 2017; and Les Iles d'Yeu et Noirmoutier, in December.
Opponents to Dieppe-Le Tréport have up to four months in which to launch appeals.
Local fishermen have long been opposed to the project, while environmentalists object to turbines being located in a protected marine area
However, Leblanc is optimistic that opposition will fade as EMDT continues an information campaign.
"We will continue to have discussions with all stakeholders and the public to keep them informed," he said.
EMDT has worked hard to reduce the environmental impact and to allow fishing within the project area.
Last year, the maritime advisory body gave a strong recommendation to allow fishing, though the final decision will not be made until just before commissioning.