This came despite minutes showing half of Fed policymakers think the programme should stop by the end of this year.
As investors cheered the prospect of ongoing support, risk assets performed strongly.
European bonds from Germany to Greece tracked gains in US debt and European shares opened up almost 1%, pushing MSCI's world index, which tracks stocks in 45 countries, to its highest in almost a month.
"Bernanke's comments were taken by the markets as much more dovish so I suspect it will be a good day for risk markets and I don't expect that to change in the near term," said Saxo bank Chairman and senior market analyst, Nick Beecroft.
"We are still in a bit of a sweet spot for equity markets. The economy is doing well enough to encourage equity markets about future earnings, but not too hot to cause the Fed to remove accommodation."
The dollar tumbled 1.2% against a basket of major currencies while the euro roared to a three-week high of $1.32085 at one stage, though it was back at $1.3038 by 0720 GMT.
Copper prices gained 3.2% to exceed $7,000 a tonne, hitting a three-week high and extending the previous session's 1.4% rise as the dollar softened.
Gold climbed 2.4% to a three-week high and was on track for a fourth straight day of gains while US crude oil prices added 0.7% to their highest level since March 2012, extending Wednesday's 2.9% jump.