Cilevičs was born in a Jewish family in Daugavpils during the Soviet occupation of Latvia.

During the Singing Revolution, Cilevičs became an activist in the Popular Front of Latvia, especially during their 1990 Latvian election campaign.

Although he ran unsuccessfully in the 1995 Latvian parliamentary election, he became an assistant to party MP Jānis Jurkāns.

From May to July 2004, Tsilevitch briefly served as Member of the European Parliament between the accession of Latvia and the first direct election of Latvian MEPs.

In addition to his role in parliament, Tsilevitch has been serving as member of the Latvian delegation to the Parliamentary Assembly of the Council of Europe since 2011.