"I expect that it will be appropriate at some point later this year to take the first step to raise the federal funds rate and thus begin normalizing monetary policy," she said in a speech in Cleveland, Ohio.
Yellen, however, remained cautious, saying she still saw slack in the jobs market, which has been a key factor in how the Fed approaches its first rate hike since 2006.
"We will be watching carefully to see if there is continued improvement in labor market conditions, and we will need to be reasonably confident that inflation will move back to two percent in the next few years," she said.
The Fed has kept its benchmark federal funds rate at zero since the end of 2008 to help pull the economy back from the Great Recession.
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Since early last year the Fed had been expected to move on rates around mid-2015, but the stall in the economy in the first quarter of the year, and the tepid rebound from that, have delayed the decision.
Addressing the City Club of Cleveland, Yellen said that the economy is near the point where it does not need the support of rates at such an extraordinarily low level.
Even with the US unemployment rate now down to 5.3 percent, its lowest level since April 2008, she said there was still some slack in the US jobs market.
"It is my judgment that the lower level of the unemployment rate today probably does not fully capture the extent of slack remaining in the labor market -- in other words, how far away we are from a full-employment economy," she said, according to her prepared remarks.
She pointed to the very low level of participation in the active work force, the high number of people in part-time jobs, and the relatively slow pace of hiring.