Welsh Secretary Peter Hain has welcomed a House of Lords ruling giving the final go-ahead to the Bluestone holiday village in Pembrokeshire.
The scheme has been subject of a long legal battle
The plans for the complex of timber lodges, a health spa, sports club and subtropical water world, have been the subject of a long legal battle.
Mr Hain said Bluestone would bring significant benefits.
The row began when Pembrokeshire Coast National Park Authority agreed for part of Bluestone to be built on park land.
A Lords committee refused on Friday to overturn planning permission for the scheme, which could create 900 jobs.
Mr Hain told BBC Radio Wales on Saturday: "This is magnificent news for Pembrokeshire and for Wales. This will be a world-class tourist attraction which will attract thousands of tourists.
"It will create hundreds of jobs and bring greater prosperity to this beautiful part of Wales."
A second phase of the development - which is set in 500 acres of Pembrokeshire countryside - will see the creation of an indoor snow dome.
The scheme has been subject of a long legal battle.
Pembrokeshire Council first gave the scheme the go-ahead in July 2003, followed by Pembrokeshire Coast National Park who gave planning permission in January 2004.
Both bodies were involved in the planning process because the scheme incorporates a small area of coastal park land.
That point became the basis for the opposition to the scheme by the Council for National Parks (CNP) - a charity that works to protect and enhance the national parks of England and Wales.
The CNP claimed the scheme established a precedent which could allow development on protected parkland across the UK.
Bluestone developers claim it would create 900 jobs
As a result, the scheme has been the subject of an independent ombudsman inquiry, which upheld the consent.
High Court Judge Justice Jacks ruled in December 2004, after a three-day judicial review, that the decision was lawful.
In June this year, at the Court of Appeal in Swansea, Lord Justices Maurice Kay, Latham and Jacob all agreed with Judge Justice Jacks' judgement.
The CNP then petitioned the House of Lords, but on Friday, an appeal committee refused a final attempt to overturn the decision, opening the way for the scheme to go ahead.
'Delighted with decision'
Lord Hoffman, Lord Scott of Foscote and Lord Walker of Gestingthorpe refused the CNP appeal stating: "Permission is refused because the petition does not raise an arguable point of law of general public importance."
Welcoming the decision, Bluestone chief executive William McNamara said: "We are delighted with this decision which was not unexpected.
"Bluestone has now passed every legal, democratic and environmental test laid before it by two planning committees, 10 statutory advisors, an independent ombudsman, a High Court judge, three Lord Justices at the Supreme Court of Appeal and now three Law Lords.
"That is 10 professional judgments that all bear witness to the propriety of the Bluestone decision and this clears the way for work to begin on this major new holiday village development in the UK."
The Council for National Parks said it was disappointed by the Law Lords' decision.
CNP chairman Kate Ashbrook said: "This major holiday village will cause tremendous damage to the Pembrokeshire Coast National Park which is why we are fighting so hard to protect the park.
"We have convened an urgent meeting of our legal advisers to consider the implications of this decision and will be issuing a full statement next week".