Born in 1966 in Agia Paraskevi, Lesbos, Vaxevanis began his journalistic career in Rizospastis in 1988. He later worked with other newspapers, including Eleftherotypia, Kathimerini, To Pontiki and To Vima.
In April 2012, Vaxevanis began the publication of the fortnightly magazine Hot Doc.
On 28 October 2012, he was arrested over the magazine's publication of a document claimed to be the Lagarde list, a list of 1,991 names of Greek customers with accounts at the Swiss branch of HSBC, suggesting that they could be tax evaders. He was charged with "interfering with sensitive personal data". The published list had names of customers of the Geneva branch of HSBC and, according to the magazine, "matched a list of 2,059 people" on the Lagarde list. Vaxevanis was released from Athens police headquarters a few hours after his arrest. On leaving the building, he told a reporter: "The prosecutor's office wants to protect tax evaders. I'm just doing my duty. Instead of arresting the tax evaders and the ministers who had the list in their hands, they're trying to arrest the truth and freedom of the press."
On 29 October, he was given a "fast-track trial date" by prosecutors. Government critics contrasted the speed of the case against Vaxevanis with the slow arrest of Golden Dawn MP Ilias Kasidiaris and the government's slow investigation of the Lagarde list itself. Following his arrest, Vaxevanis wrote an article for the British newspaper The Guardian describing his view of the circumstances behind the publication of the list. The New York Times condemned the prosecution in an op-ed titled "Greece Arrests the Messenger", stating, "Greece’s elected leaders need to pay more attention to investigating possible financial crimes and less to prosecuting journalists."
Vaxevanis' trial began on 1 November and ended the same day with an acquittal. Leaving the courtroom, he quoted George Orwell to supporters: "Journalism is printing what someone else does not want printed. The rest is public relations." On 16 November, the courts indicated that he may face retrial. In 2013, a prosecutor overturned the acquittal and ordered Vaxevanis to undergo a new trial. The retrial ended in November 2013 with another acquittal.
- "Κώστας Βαξεβάνης" (in Greek). Retrieved 2012-10-30.
- "Κώστας Βαξεβάνης" (in Greek). Retrieved 2015-02-10.
- "Greece arrests journalist over 'Lagarde List' banks leak". BBC. 28 October 2012. Retrieved 28 October 2012.
- Borger, Julian (28 October 2012). "Greek magazine editor in court for naming alleged tax evaders". The Guardian. Retrieved 29 October 2012.
- Donadio, Rachel (29 October 2012). "Greece Moves Quickly to Put Editor on Trial". The New York Times. Retrieved 30 October 2012.
- Alderman, Liz (28 October 2012). "Greek Editor Is Arrested After Publishing a List of Swiss Bank Accounts". The New York Times. Retrieved 30 October 2012.
- "On the Trail of Lost Taxes in Greece". Deutsche Welle. 29 October 2012. Archived from the original on 31 October 2012. Retrieved 30 October 2012.
- Vaxevanis, Kostas (30 October 2012). "Greece gave birth to democracy. Now it has been cast out by a powerful elite". The Guardian. Retrieved 30 October 2012.
- "Greece Arrests the Messenger". The New York Times. 29 October 2012. Archived from the original on 31 October 2012. Retrieved 30 October 2012.
- Magnay, Diana (November 1, 2012). "Greek journalist on trial over printing Swiss bank account list". CNN. Archived from the original on 1 November 2012. Retrieved 1 November 2012.
- "Greek bank list editor Costas Vaxevanis acquitted". BBC News. 1 November 2012.
- Kakissis, Joanna (1 November 2012). "A Crusading Journalist's Arrest Spurs Greek Anger". NPR. Retrieved 2 November 2012.
- Smith, Helena (November 16, 2012). "Greek editor Kostas Vaxevanis faces retrial over 'Lagarde list' revelation". The Guardian. Archived from the original on 16 November 2012. Retrieved 16 November 2012.
- Smith, Helena (27 November 2013). "Greek court acquits editor who leaked 'Lagarde list' of suspected tax evaders". The Guardian. Retrieved 27 November 2013.
- Caravaca, Toñi (7 April 2013). "Kostas Vaxevanis, el 'hermano' de Julio A. Parrado". El mundo. Retrieved 7 April 2013.