His supporters broke into thunderous applause and chanted “tongai, tongai baba” [rule, rule father] as the Zanu-PF annual conference in the south-eastern town of Masvingo nominated Mr Mugabe on Saturday.
In his acceptance speech, Mr Mugabe called for an end to party infighting.
“We agreed that conflicts should end. Infighting should end. The party ideology should be followed,” he said.
“Let us be one. We are one family, the family of Zanu-PF bound together by the fact of understanding between its members.”
Mr Mugabe has blamed the country’s economic problems on sabotage by Western critics of his policies.
Amid violent protests earlier this year he warned there would be no Zimbabwean uprising similar to the “Arab Spring”.