Another opposition member of parliament, Godfrey Sithole, was also found guilty after the year-long trial.
Sentencing will take place later, after a mitigation hearing on Monday next week.
Authorities accused the two of inciting supporters to avenge the death of their political ally Moreblessing Ali, who was murdered by a ruling party activist in May 2022.
Harare-based magistrate Tafadzwa Miti said "the state proved its case beyond reasonable doubt" as she delivered her judgement before a packed courtroom.
Scores of anti-riot police were deployed at Harare magistrates court blocking friends of the accused, and one pointed a pistol towards one of the defence lawyers, AFP saw.
The magistrate ruled that the pair incited public violence by ferrying mourners to Ali's memorial service, which was marred by violence.
Miti also said the State proved that Sikhala had said the area "should be turned into a terror zone" which was captured in a video published on social media.
"To incite is to influence the mind of another to commit public violence, this can also be by gesture," she said. "As such the two accused persons are found guilty as charged."
Ali was abducted from the Nyatsime area by an activist of the ruling Zanu PF party. Her decomposing body was found 21 days after she went missing.
A memorial service for Ali was held days later and political violence erupted, leaving a trail of destruction in the area.
Sikhala and Sithole were blamed, with prosecutors alleging that two connived to cause unrest.
Following his arrest, Ali's family refused to bury her remains which are believed to be in a government mortuary.
Sikhala has been in jail since June 14 after he failed to secure bail. Sithole is free.
Some opposition supporters collapsed in despair when the verdict was reached, but Sikhala himself remained upbeat and urged his relatives not to worry.
His lawyer, Harrison Nkomo said he intended to appeal.
A number of civil rights activists and opponents of President Emmerson Mnangagwa have been arrested since he succeeded Robert Mugabe in 2017.
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