Much of the upward revision came from stronger consumer spending, the Commerce Department said on Friday.
The final revision of the third-quarter figure was up from a previous estimate of 3.6%, which in turn was far above forecasts of around 2.8% made earlier.
Four-fifths of the revision came from stronger consumer spending, primarily in the area of healthcare, said the Commerce Department.
The 4.1% third-quarter growth rate came after the economy expanded at a 2.5% rate in the second quarter. Much of the acceleration reflected a buildup in business stockpiles.
However, economists believe growth has slowed to between 2% and 2.5% in the current quarter, in part because they believe inventory growth has slowed.
In any case, the US Federal Reserve declared this week that the economic recovery was sufficiently solid that it could start to scale back its massive stimulus spending.
Starting in January, it will reduce its monthly asset purchases to $75 billion from $85 billion, it said this week.