In a joint statement, Brown and Iraqi Prime Minister Nouri al-Maliki said the British forces will have "completed their tasks" by mid-2009 and that the role played by U.K. troops is "drawing to a close."
Confirmation of the plan came at a press conference in Baghdad Wednesday, one day after the Iraqi government drafted a law providing for the withdrawal of non-U.S. forces by mid-summer. There are 4,100 British troops stationed in the southern Iraqi city of Basra.
News of the withdrawal plan was leaked earlier this month to British news organizations. Between 200 to 300 military advisers are likely to remain In Iraq after combat troops leave, the BBC reported.
"We have agreed today that the mission will end no later than 31 May," Brown said at the news conference with al-Maliki during a visit to Baghdad. "Our troops will be coming home within the next two months [after that]."
Al-Maliki thanked the British troops for their part in ridding the country of dictatorship.
"They have made a lot of sacrifices," al-Maliki said.
The draft Iraqi law on non-U.S. coalition forces sets the end of May as the final date for combat operations and the end of July as the withdrawal date. Earlier this month, Iraq and the United States agreed on a security pact allowing some 140,000 U.S. forces to remain in Iraq until the end of 2011.
Brown estimated 100,000 British soldiers have served in Iraq since 2003. At one point, there were 45,000 British troops in the country but that number has slowly been reduced to the 4,100 based near Basra.
Britain's defense ministry said U.S. troops are expected to take over the base near Basra's airport once U.K. forces leave, reported the Associated Press.
Britain does not plan to send any additional troops to Afghanistan, but has said it will transfer helicopters from Iraq to the other war zone. There are 8,300 British troops serving in Afghanistan, according to Reuters.
The news conference occurred without incident, in contrast to Sunday's Baghdad press conference with President George Bush, where an Iraqi journalist lashed out at Mr. Bush and threw his shoes at him from close range. The journalist, Muntadhar al-Zeidi, who is in jail, appeared before a judge Wednesday.
Brown also said he and al-Maliki discussed the fate of five British citizens who were kidnapped by a Shiite militia over a year ago. An information technology consultant and four guards were seized from the Iraqi Finance Ministry compound in Baghdad in a raid in May 29, 2007.
"I call for all those who are holding them to let them return to their families immediately and without condition," Brown said.
A total of 178 British troops have died since the invasion, reported the AFP, including 136 killed through hostile action.
While security in Iraq has seen gains over the past year there are still sporadic attacks. Shortly after the meeting with Brown, bomb blasts in Baghdad killed 18 people and wounded 53.