In addition to tax cuts for families and businesses, the plan would pay for construction and repair of roads and schools and provide aid to US cities and states, Obama said.
Obama has previously said he was considering a plan in the range of $775 billion, though he has suggested the final cost could exceed that.
He gave no precise figure in Thursday's speech although Obama listed $1,000 tax cuts for middle-class families as one element of the package.
Wall Street warning
The US president-elect also once again promised tougher regulations on Wall Street traders.
"No longer can we allow Wall Street wrongdoers to slip through regulatory cracks. No longer can we allow special interests to put their thumbs on the economic scales," he said.
Wall Street firms have come under renewed scrutiny after the global financial crisis rocked world markets last year.
The crisis hit a US economy already struggling in the wake of the subprime mortgage crisis, which occured after millions of Americans were granted high-interest mortgages they were unable to repay.
A report on Wednesday showed the fiscal deficit for 2009 would triple to around $1.2 trillion, even before taking into account the cost of the stimulus package.