The visit is under heavy security and is the first by a top U.S. official since the new Iraqi government was formed at the end of last month. The visit appears intended to show support for moving Iraq's political process forward to combat the insurgency.
Rice flew today from Qatar to Iraq, landing first in Irbil in the Kurdish-administered area of northern Iraq.
From there she moved immediately to nearby Salahuddin for talks with one of the two main Kurdish leaders, Mas'ud Barzani.
Then, she flew on to Baghdad. Speaking at the U.S. Embassy compound in the center of the city, she said she was pleased to be in the Iraqi capital.
"What a thrill to be in Baghdad," Rice said. "I can't tell you how excited I've been about coming. How delighted I am to be here. I just took the helicopter ride in. This is a spectacular city. It really is."
She also said that the U.S. involvement in Iraq is part of a larger necessity to build democracy in the Middle East.
"We had to have a chance to work with people in the Middle East who wanted a different kind of life because the absence of freedom in the Middle East -- the freedom deficit -- is what has produced the ideologies of hatred that led people to fly airplanes into buildings on a fine September day," Rice said.
In Baghdad, Rice was due to meet with top Iraqi officials including transitional Prime Minister Ibrahim Ja'fari and President Jalal Talabani.
While in Iraq, the top U.S. diplomat is expected to press Iraqi officials to move the political process forward in order to combat the insurgency.
Many ordinary Iraqis have expressed dismay that it took Iraqi leaders three months to form a new government following the country's landmark elections for a National Assembly at the end of January.
There are also continuing problems over how to assure adequate involvement of Iraq's once-dominant Sunni minority in the political process after much of that community boycotted the poll.
Rice told reporters on the plane from Qatar that she believes the insurgency in Iraq can be beaten if Iraqis are provided a strong political alternative.
"The insurgency is very violent but you defeat insurgencies not just militarily -- in fact not especially militarily -- you defeat them by having a political alternative that is strong," she said.
She also said she would discuss reconstruction efforts in Iraq and plans for a new donor conference in June sponsored by Washington and the EU.
Rice's visit comes on a day with mixed reports of progress against Iraq's insurgency. The U.S. military said that its troops have successfully completed an offensive against insurgents in western Iraq near the border with Syria.
But Iraqi authorities also announced that the bodies of 34 people had been found in three separate locations around the country.
Insurgent attacks have killed more than 400 people in Iraq since the new government was formed on 28 April.[For the latest news on Iraq, see RFE/RL's webpage on "The New Iraq".]