Mugabe was endorsed by the central committee despite being widely blamed for the political and economic crisis in Zimbabwe.
Nathan Shamuyarira, the party spokesman, said: "The candidate for the party in 2008 will be the president himself. He was endorsed by the central committee."
Also on Friday, Mugabe said that Morgan Tsvangirai, the opposition leader, had been assaulted, and that he deserved it.
He told supporters the day after returning from a regional summit in Tanzania: "Yes, I told them he was beaten but he asked for it."
Mugabe said: "We got full backing, not even one criticised our actions.
"There is no country in SADC (the Southern African Development Community) that can stand up and say Zimbabwe
"SADC does not do that, it is not a court but an organisation of 14 countries that co-operate with each other and support each other."
Tsvangirai's arrest and subsequent assault on March 11 while trying to attend an anti-government rally was widely condemned by the West.
But the SADC summit, which was meant to address the crisis in Zimbabwe, ended up with a statement of "solidarity" with the 83-year-old Mugabe's government.
Mugabe's decision to seek another term in office was denounced also by a breakaway faction of the opposition MDC, which said it would set the country back.
Priscilla Misihairambwi-Mushonga, secretary-general of the faction, said: "The leadership of the ruling party has failed this country and they will have to explain this to future generations of what they did."
Sean McCormack, a US state department spokesman, called the decision "sad" and "outrageous", adding that "we hope better for the Zimbabwean people".
"The situation in Zimbabwe obviously can't continue as it is," he said, referring to the deteriorating economy and humanitarian situation under Mugabe's government.
The US also chided Zimbabwe's neighbouring states for not taking a firmer stand against a recent violent crackdown by Mugabe's government on his political opponents when they held a regional summit meeting this week.