Despite his first court victory, Job Sikhala, 51, will remain in custody, his lawyer said.
A Harare appeals court overturned a conviction of obstructing the course of justice in a case stemming from the murder of another opposition activist.
"The conviction and sentence is quashed and set aside," Judge Benjamin Chikowero told the court.
Sikhala was convicted in May after he allegedly blamed the ruling ZANU-PF party for the death of Moreblessing Ali, an activist for the Citizens Coalition for Change, CCC.
Ali's mutilated body was found in a well last year.
Prosecutors alleged that Sikhala's words diverted investigations focused on other suspects.
It was the first time the firebrand politician had been found guilty during a troubled career, which includes more than 60 arrests, according to his lawyers.
"You don't have to worry about me. Don't cry. Be strong for me, everything will be alright," Sikhala said in court, comforting a relative who broke down before the proceedings.
His lawyer, Harrison Nkomo, said that the charismatic Sikhala would remain in custody "because there are many cases against him."
The former lawmaker was initially arrested in June 2022 on allegations of inciting public violence following Ali's death.
At the time he was already facing trial on accusations of inciting violence and publishing falsehoods related to other cases.
He was slapped with additional charges of obstructing the course of justice while in custody.
The conviction barred him from contesting national elections held in August, which were won by ZANU-PF amid opposition allegations of fraud.
International observers said the vote fell short of democratic standards and political tensions have since run high. The CCC says its members have faced a campaign of intimidation.
Critics have long accused ZANU-PF, which has been in power since independence in 1980, of using the courts to silence dissent.
"As we express gratitude, let us remain resolute in our determination to continue the struggle until Job Sikhala and all political prisoners are free," Obert Masaraure, a spokesman for Crisis in Zimbabwe Coalition, a civil society umbrella group, told AFP.
Zimbabwean Court Overturns Opposition Figure Conviction, Several Charges Remain
FILE —Zimbabwean opposition figure Job Sikhala, is seen inside the court following his conviction in Harare, May 3, 2023.
HARARE — A prominent Zimbabwean opposition figure jailed since last year was found not guilty on Tuesday of one of several charges his supporters say are politically motivated.