Cierliukievič came to nationwide prominence at a rally at the main square of Minsk on 21 August 1991, the last day of the anti-Gorbachev August Coup. The event was organized by the Belarusian Popular Front to protest against attempts to take control of the country by reactionary Communist leaders and reverse democratic reforms. Cierliukievič addressed the protesters alongside key opposition leaders such as Zianon Pazniak,  Piatro Sadoŭski, and underlined the important role of workers in the democracy movement.