"My colleagues and I took this action to help the US economy keep strong in the face of new risks to the economic outlook," chairman Jerome Powell said.
US president Donald Trump called for more action after the decision, having earlier pointed to Australia's central bank cutting interest rates to a record low of 0.5% yesterday.
"More easing and cutting!" he tweeted.
European and Australasian markets were mixed and key North American indices closed lower.
Futures were also mixed.
Gold was above $1,644/oz on the spot market at the time of writing.
Gold major Newmont (NYSE: NEM) leapt 6.2% yesterday to within a whisker of last month's multi-year high.
Among the diversified miners, Glencore (LSE: GLEN) closed just over 1% lower in London and BHP (ASX: BHP) was down 0.9% in morning trade.
