Jacob Ngarivhume was arrested along with journalist Hopewell Chin'ono on 20 July, on charges of inciting violence. Ngarivhume had called for the protests on 31 July and Chin'ono wrote about the call.
Both men had been denied bail three times, but on Wednesday High Court judge Siyabona Musithu said the politician would be released from detention at a maximum-security prison after paying 50 000 Zimbabwe dollars ($600).
The judge said a lower court had erred in denying Ngarivhume bail. Another judge will rule on whether to free Chin'ono later on Wednesday.
As part of bail conditions, Ngarivhume, who leads a small opposition party, Transform Zimbabwe, was barred from posting on Twitter until his case is finalised, must surrender his passport to the court and report to the police three times a week.
Prevented from protesting by restrictions the government says are needed to stop the spread of Covid-19, activists have used a Twitter hashtag #ZimbabweanLivesMatter to criticise President Emmerson Mnangagwa and encourage global pressure on his government.
When Chin'ono made a routine court appearance on Tuesday, he looked visibly frail and told reporters that he was unwell and doctors had taken a sample to test for Covid-19.
The detention of Ngarivhume and Chin'ono and arrest of dozens of activists has led to accusations that the government is persecuting the opposition, a charge the authorities deny.
The opposition has disputed Mnangagwa's 2018 election, which took place after he replaced ruler Robert Mugabe in a coup, promising a break with Mugabe's authoritarian style.
