The East Rhyl Coastal Defence Scheme, funded by Denbighshire County Council and the Welsh Government, is set to protect 1,650 properties in East Rhyl from coastal flooding.
Works began in April 2020 and were due to end in December 2022, however the scheme has been completed ahead of schedule, the council said.
The successful placement of 128,000 tonnes of rock armour in front of the existing sea defences at East Rhyl and the newly added 600 metres of sea defence wall and promenade will protect the area from current storms and the impact of climate change.
Principal contractors Balfour Beatty undertook the majority of works.
According to the council, community benefits from the scheme included a beach access gate at Old Golf Road for use at weekends, renovation works at the Splash Point and the donation of Groynes to the RNLI for their memorial area and to Friends of the Cob for the Glan Morfa site.
Other benefits included using the North Wales supply chain for rock deliveries, a virtual mentoring session with Working Denbighshire to help those looking or work in the construction industry and donations to Sussex Street Food Bank.