The decision, which surprised some investors, will ease efforts to boost the country's economy by lowering interest rates and boosting activity. It will be cut by £11.6bn a month.
The Federal Reserve's governing committee cited stronger job growth as a reason for the decision. It is being suggested the central bank now believes that the US economy is finally strong enough to no longer need as much support. It said: "The committee sees the risks to the outlook for the economy and the labour market as having become more nearly balanced."