He told a London dinner organised by Business in the Community and the business-based Percent Club: "We will only have one chance.
"Indeed, if we fail the first time, disillusionment and cynicism will prevent us being able to mount this again."
Because of that imperative, the Chancellor said, the Government was prepared to consider radical solutions.
Speaking to an audience that included the Prince of Wales, who is president of Business in the Community, and founder of the pace-setting Prince's Trust Volunteers, the Chancellor said that the Government wanted to build on existing success, not start afresh.
That meant breaking down barriers between public and private provision, using private employment agencies where relevant, and allowing grassroots organisations and officials to "rewrite the rules", if that would get results.
"We make what works our guiding light," Mr Brown said.
"But we remember all the time, our goal is not just to take people off the streets for six months but to make the unemployed employable."
The alternative was the threat of "exclusion for an entire section of a generation of young people" from the 400,000 youngsters out of work.
In a direct appeal for their cooperation and support in the Welfare to Work programme, the Chancellor told his business audience: "In some of our poorest communities, one-third of all young people are doing nothing, and in some of these, there is second generation unemployment: the culture of work destroyed."
Mr Brown also warned that was not only a social and financial waste, but a waste of potential that required business and the community to work together to provide a solution.
The business dinner was the Chancellor's first official engagement with Prince Charles, who hosted the event.Reuse content