The index that tracks a variety of business activities rose to 104.1 in the month after rising 0.4 percent in December and falling 0.1 percent in November.
The monthly survey found "business, consumer and financial market confidence has improved following the December European Union summit and the start of the European Central Bank's Longer-Term Refinancing Operations," the Conference Board said.
The index indicates the eurozone, which is predicted to fall into a mild recession in 2012, "may manage to contain the debt crisis and avoid a longer and deeper recession," the report said.
The monthly Coincident Economic Index, which measures current business activity was unchanged in January at 102.6.
Both the leading and coincident indexes use 2004 as a base year, assigning that year a value of 100.