US Embassy spokesman Bob Callahan said Powell was met on Friday at Baghdad International Airport by US Ambassador John Negroponte.
Callahan told Associated Press Powell would meet top Iraqi officials, including the country's interim president, Ghazi al-Yawar, and deputy prime minister, Barham Salah, before leaving later on Friday.
Powell arrived in Iraq after meeting Kuwaiti and Saudi leaders in their respective countries.
The US secretary of state's Friday visit was the first by a senior US official since the handover of power to an Iraqi government on 28 June.
In the Saudi port city of Jidda on Thursday, Powell met interim Iraqi Prime Minister Ayad Allawi, who urged Muslim nations to dispatch troops to Iraq to help defeat resistance he said threatened all Islamic countries.
Allawi made the appeal a day after Saudi officials disclosed they had initiated an effort to encourage the creation of a Muslim security force to help bring stability to Iraq.
Powell welcomed the Saudi initiative and said the time might be ripe for a more active role by Arab and Muslim countries based on the handover of power to Allawi, along with the approval of a UN Security Council resolution that gave legitimacy to his interim government.
Under the Saudi proposal, Arab and Muslim countries that do not border Iraq would be invited to contribute. Baghdad opposes deployment of foreign troops from neighbouring countries, fearing these nations will fuel divisions within the country by providing support to Iraq's mosaic of ethnic and sectarian communities.
Powell also said Allawi had sent letters to leaders in some Arab and Muslim countries inviting them to dispatch forces.