"And so I think we ought to keep on the track that we are on," the Republican, who also backed Obama in 2008, told "CBS This Morning."
The move comes just days after Obama and Republican challenger Mitt Romney clashed over foreign policy in the third and last presidential debate ahead of the November 6 election.
Polls show a tight race between Obama and Romney. A Reuters/Ipsos online tracking poll gave Romney a 1-point edge on Wednesday, 47 percent to Obama's 46 percent.
Powell criticized Romney's foreign policy as inconsistent and questioned the former Massachusetts governor's ability to tackle the deficit and looming defense cuts.
"I'm not quite sure which Governor Romney we'd be getting with respect to foreign policy," Powell said, calling Romney's foreign policy "a moving target."
As for the U.S. budget, he added: "It's essentially let's cut taxes and compensate for that with other things, but that compensation does not cover all the cuts intended or the expenses associated with defense."
