Critics have slammed the trial as an attempt to eliminate a key opponent of Turkish President Recep Tayyip Erdogan.
The mayor of Istanbul has been jailed for "insulting" officials in a controversial trial ahead of next year's elections.
Ekrem İmamoğlu was convicted of "insulting" members of Turkey’s Supreme Electoral Council and sentenced to two years and seven months in prison.
The Turkish court also imposed a political ban that prevents him from standing for election over the same period.
Critics have slammed the trial as an attempt to eliminate a key opponent of Turkish President Recep Tayyip Erdoğan before the presidential and parliamentary elections in June 2023.
The 52-year-old mayor, who belongs to the main opposition Republican People’s Party (CHP), is expected to appeal the court's ruling.
İmamoğlu has always professed his "confidence in Turkish justice" and has condemned the case as "political".
Thousands of protesters gathered in front of the municipality building in Istanbul on Wednesday to denounce the verdict.
İmamoğlu was elected to lead Istanbul, Turkey's most populous city, in March 2019.
His win was a historic blow to Erdoğan's ruling Justice and Development (AK) Party, which had controlled Istanbul for 25 years.
After claiming that there were irregularities with the initial municipal election results, a repeat vote also saw İmamoğlu win.
The popular Istanbul mayor was charged with insulting senior public officials after he described their decision to invalidate his election win as an act of “foolishness”.
İmamoğlu denied the allegations and said his remarks were in response to disparaging comments by Turkish Interior Minister Süleyman Soylu.
Istanbul's mayor is seen as a rising star of Turkish politics and a potential candidate to challenge President Erdogan in June's elections.
CHP leader Kemal Kilicdaroglu said he had cut short a visit to Germany to return to Turkey and lend his support to İmamoğlu.
The court's ruling could eventually see İmamoğlu removed from office.