"I always thought a solution would be found," Lewis said. "I never gave up talking to colleagues in other unions in Europe and we were all trying to reach the same conclusion."
The leading clubs in France and England had threatened a boycott of Europe's top club rugby contest next season as part of an ongoing row about representation at boardroom level.
The threat of the removal of Heineken Cup fixtures in the rugby calendar forced Lewis to address the financial impact of losing a minimum of six games next season.
"I put in place contingency plans to generate extra money for our game at the regional level," he said. "But I am hugely relieved that ERC and the clubs have agreed to a full strength Heineken Cup next season."
Lewis was keen to stress the importance of the Heineken Cup for European rugby.
"The very future and fabric of the game would have been undermined if they hadn't sorted this out," he added. "In Welsh rugby the stepping stones have to be carefully laid out. Unless we have regional rugby playing in the Magners League and at the very highest level in Europe it will affect our performances at international level.
"If we have the right stepping stones in place, which we do now, we can play and succeed at the highest level."
This was a view echoed by WRU Chairman David Pickering. He said, "A strong Heineken Cup is what the global game needs and I'm delighted that Roger Lewis has kept the WRU at the very heart of these tough and complex negotiations."
In a short statement delivered to the press yesterday, ERC Chairman Lux said: "I would like to thank all of ERC's stakeholders who have been involved in the discussions and I am delighted to be able to confirm the future of both tournaments on the day of the 12th Heineken Cup final.
"ERC's stakeholders will meet shortly to finalise the agreement that will secure the long term future of both tournaments."
The precise details of the tournaments are yet to be confirmed, but Wales will have four sides competing in the Heineken Cup after the Dragons won their qualifying match against Italian side Calvisano 22-15.