Charles Hendry’s independent report into the technology’s viability said it would make a “strong contribution” to the UK’s energy supply.
He said it was cost effective and would bring “significant economic opportunity”.
The UK government still needs to agree on a deal and a marine licence would also need to be approved.
Mr Hendry said moving ahead with a pathfinder lagoon off the Swansea coast should be seen as a “no regrets” policy.
There are hopes of developing a network of larger lagoons around the UK coast, harnessing power from the ebb and flow of the sea’s tides.
But Mr Hendry believed that was “too ambitious a goal” before even one had been built and “could only be considered properly when more progress had been made”.