Samuel Undenge, an energy minister in Mugabe’s cabinet, has become the first member of the Mugabe government to be convicted since the long-serving leader resigned in November.
He was accused of issuing a $12,650 contract without due tender to a company that did no work.
His lawyer Alex Muchadehama said that he would appeal the court’s decision, saying the sentence was “shocking”.
He will however only serve two and half years of the four year sentence after the court said 18 months would be conditionally suspended.
Former foreign minister Walter Mzembi faces charges of “criminal abuse of office”, and former finance minister Ignatius Chombo has been charged tried to defraud the central bank over a decade ago. They both deny wrongdoing.
The southern African nation chooses a new president and members of parliament on July 30 in what is expected to be a close race between Mnangagwa’s ZANU-PF and the opposition Movement for Democratic Change (MDC).
A poll published on Friday showed the vote would provide no clear winner, with 40 percent of voters choosing Mnangagwa and 37 percent his opponent, Nelson Chamisa.