In 1980-1991 Vazniak served in the Armed Forces of the USSR (Urals Military District, Group of Soviet Forces in Germany, and the Belarusian Military District) in the following positions: deputy commander of the automotive company for political affairs, secretary of the Komsomol committee of a missile battalion, assistant chief of the political department of a tank regiment, senior instructor of Panzer Army political department, and senior instructor of the political department of the military district.
Since 1992 he has worked in journalism: as a reporter and head of the military newspaper For the Glory of the Motherland (1992-1993), as head of the press service of the People's Movement of Belarus (1993) and as a correspondent and deputy chief editor of We and Time (1994-1995). He has been chief editor of the Comrade newspaper since 1996.
He was a member of the CPSU (from 1982) and the Party of Communists of Belarus (from 1992). He was the first secretary of the Young Communist League (1992-1997) and a member of the Central Committee of the Belarusian Communist Party (1993), now the Fair World party.
During the 2010 presidential election he worked in the headquarters of presidential candidate Uladzimir Niakliajeŭ. He was arrested on 20 December in his apartment and placed in the KGB detention center. On 20 May 2011 he was sentenced to 2 years imprisonment on a suspended sentence.