The 6.7-kilometre long lagoon is being developed by Mostyn SeaPower, a subsidiary of the Port of Mostyn. The scheme would run along the Dee estuary in Flintshire from the breakwater at Mostyn to Point of Ayr.
At two metres above sea level, the lagoon wall would also provide flood protection for the low-lying land along the Flintshire coast, including an arterial road and railway, and would feature a road and public path running along the top, a statement from the firm said.
The scheme proposes eight 16-megawatt turbines which would generate 300 gigawatt hours of electricity annually from the lagoon. The developer claimed this would be able to power 82,000 homes in north Wales.
The firm said that preparatory work, including environmental and ecological studies, has been taking place for four years and the lagoon is designed to maintain navigational access for shipping.
The statement said the company intends to submit an application to the UK government for a development consent order (DCO) by the end of 2022 and anticipates gaining approval within a year.
It said the "relatively small" project would create 300 jobs during construction, which is expected to take four years, and up to 30 high-skilled permanent posts. Power is expected to be delivered to the nearby Connah's Quay power station from mid-2027, it added.
Port of Mostyn managing director Jim O'Toole said: "This will be the biggest infrastructure project north Wales has seen for a very long time and it will provide a massive and timely boost for the regional economy.
"The relatively small scale of the Mostyn SeaPower project will pave the way for future larger scaled projects around the Welsh coast."
Earlier this month, the firm behind plans to create a larger tidal lagoon across Swansea Bay in south Wales, said that works it carried out shortly before development consent for the scheme was due to expire had secured approval for the proposal "in perpetuity" - although both the local council and the government claimed the permission had expired.