Haley's official endorsement will come Friday afternoon in Greenville, S.C., but the Republican governor explained her reasons Friday morning in an interview on "Fox and Friends."
Haley said Romney knows what it's like to turn broken companies around; she noted his success fixing a failed Olympics; and she said he "knows what it's like to make a decision, and lead."
For Haley, the 2012 election is about jobs, the economy and spending.
"As governor of Massachusetts, what we saw is he (Romney) balanced his budget and he cut taxes 19 times with an 85-percent-controlled Democratic Legislature. That says a lot, and that's something that we need from a good conservative governor at this time."
Haley said the only way to get the economy moving and more people working is to "go with someone who's done it-- not talked about it, but actually done it."
Haley said she's spoken with every Republican candidate except for Ron Paul, who never called her.
"And what I will tell you is, you put all these candidates together and you've got one perfect candidate. But you're never going to have a perfect candidate. So what you do is, you look at the times of the day -- you look at what we need in the country -- and you say, let's get on track, let's get behind the person and let's make this happen."
On top of that, she said, is the fact that Romney is the one candidate that President Obama doesn't want to run against.
Romney, speaking at Thursday night's debate in Iowa, ruefully admitted that he had declined an invitation by the founder of JetBlue to invest in the airline. He was making the point that he has learned from his failures as well as his successes.
Haley said, "When someone can go and say that they've learned from mistakes and successes, that's someone that's ready to lead. You know, we're dealing with a president now that refuses to admit that he's ever done anything wrong, that there is any need for improvement.
Haley compared Romney to Reagan in that both men learned to be "a great candidate" by running unsuccessfully for president the first time.
The South Carolina primary takes place on Jan. 21.