Economy Secretary Ken Skates announced £324,000 of EU and Welsh Government funding for a feasibility study for the South Pembrokeshire Demonstration Zone.
It would allow developers to test wave energy converters able to generate up to 100MW of green electricity.
It is hoped the test will act as a catalyst for a marine energy production centre at Milford Haven.
The study will be conducted in two phases by Wave Hub Ltd and will cover 34.7 sq miles (90 sq km) of sea bed off the coast.
It comes a week after the £1.3bn Swansea Bay City Region deal was signed which includes a £76m project to establish a marine energy centre around the port of Milford Haven for marine energy development, fabrication, testing and deployment.
Plans for a massive wave-energy generating centre off the west Wales coast have moved a step closer.