Britain's economy could continue to grow despite fallout from the global credit crisis, Brown told an audience of business leaders, pledging a risk-free fiscal strategy.
"In difficult times we have been able to and will continue to hold to a stable course," Brown told a meeting of the Confederation of British Industry.
He pledged to maintain economic stability, develop London as the center of a global carbon trading market and prepare young people for a sharply declining number of unskilled jobs.
"We will take no risks," Brown said. "No unfunded spending commitments, no unaffordable promises and no short-term giveaways."
Brown said he backed plans to expand Heathrow airport - Europe's busiest - with a third runway, a proposal strongly opposed by environmental groups.
He said the 16 billion (US$33billion; EUR22billion) Crossrail project, to install a new east-west rail line through London, will also go ahead, pledging to simplify planning rules for similar major projects.
Crossrail was first approved in 1990, but has been put off repeatedly because of growing cost estimates.
Brown said there was a clear imperative to increase capacity at airports.
"Our prosperity depends on it: Britain as a world financial center must be readily accessible from around the world," he said.
Opponents claim his commitment to new transport links cannot be squared with a pledge to make Britain a world leader in combatting climate change.
Brown said last week he is considering whether Britain can meet an 80 percent cut in carbon emissions by 2050. He has already pledged a 60 percent reduction.