An 18-month prison term and forfeiture of 33 million won ($21,800) were sought Wednesday for Seoul Mayor Oh Se-hoon at Seoul Central District Court.
The special counsel team led by Min Joong-ki said Oh accepted illegal political funds tied to opinion polls he received before the 2021 Seoul mayoral by-election.
Oh was indicted in December on charges of violating the Political Funds Act, moving the case into the sentencing phase.
The prosecution request puts one of South Korea's highest-profile local leaders at risk of criminal punishment over campaign-related financing.