He graduated from the University of Athens and studied journalism in Paris, Tokyo and India.
He is the creator of the news web channel "TVXS". He has worked as a political correspondent in Greece and as a foreign correspondent in Paris and Moscow, from where he covered developments in the Soviet Union and the other ex-communist countries. In the 1992-1995 period he covered the war in Yugoslavia as a special war correspondent.
In 1996 Kouloglou created and introduced for the Greek national television Reportage Without Frontiers.
On November 1, 2008 he began an internet channel named "television Without Frontiers", a news and political analysis website. On May 12, 2008 the administration of ERT decided not to renew the cooperation with the journalist.
As justification, they said that the broadcast had run its course and that its cost was disproportionally high According to Kouloglou, the ERT administration had requested the cancellation of the broadcasting of his documentary show titled "Young Workers for 700 €", while they also refused to cooperate in the organization of a documentary on human rights in China from Mao to the Olympic Games.
The termination of his cooperation with ERT was portrayed as "censorship" by politically friendly to the journalist media and a few like-minded deputies in the parliament. appointed by the new government.
He has written books on current affairs and politics (Sta ihni tou Tritou Dromou, 1986 (On the footsteps of the "Third Road"), Mia fora ki enan kairo itan mia Sovietiki Enwsi, 1994 (Once upon a time there was a Soviet Union), Oi kokkinoi ksanarhontai, 1994 (The return of the Reds)), historical testimonies (Martyries gia ton Emfylio kai tin Elliniki Aristera, 2005 (Testimonies on the Civil War and the Greek Left)). He also wrote two novels, Egklima sto proedriko megaro, 1989 (Crime in the Presidential House) - a book exposed as plagiarism from Asesinato en el Comité Central (Murder in the Central Committee), 1981 by Vázquez Montalbán and "Minister pas pote monos sto tahydromeio"("Never Go to the Post Office Alone"), 2002. He is producer and director of numerous grand reportages and documentaries for ARTE, ERT, including «Whistleblowers»(2004).
Among his documentaries stands out "Oligarchy" (2012) a documentary on the world financial crisis filmed in the United States, Germany, Belgium, Great Britain, Spain, Portugal, Ecuador and Greece.
«Holocaust of Memory»(2013), is a breathtaking documentary about personal testimonies on unreported nazi crimes in Greece. His documentary titled "The godmother" (2014) focuses on Angela Merkel and her strategy to impose German hegemony in Europe.
His latest documentary "Escape from Amorgos" (2015) is a sensational story about the exiled politician Giorgos Mylonas and true face of the military dictatorship in Greece.
Early 2015, Stelios Koulogou was designated member of the European Parliament on behalf of Syriza, after Georgios Katrougalos joined the Greek government as Minister for Administrative Reforms. On January 28, 2010 Stelios Kouloglou returned to ERT as member of the Hellenic Broadcasting Corporation"s (ERT) board.