Defterios started as an intern at CNN when the network was launched in the early 1980's. He worked for Reuters Television from 1984 to 1992, serving as European correspondent and special series producer for Nightly Business Report, a joint venture with PBS.
In 1988, Defterios served as European Correspondent and Bureau Chief based in London, managing the editorial joint-venture with Reuters Television. In that post, Defterios covered the fall of the Berlin Wall. In 1990-91, Defterios covered the Gulf War from Kuwait.
He has been a media leader of the World Economic Forum in 1996, chairs the "CNNMoney Roundtable" at the annual meeting in Davos and in 2013 chaired the St. Petersburg International Economic Forum with Vladimir Putin and Angela Merkel.
He joined CNN in 1992, serving as a correspondent for Lou Dobbs Moneyline in New York City. He hosted World Business Today from 1994 to 1996 in London. He also served as anchor of Ahead of the Curve and Business Unusual and was principal anchor for CNNfn in New York. Since October 2007, Defterios has been hosting Marketplace Middle East on CNN International. In November 2011, he began presenting Global Exchange, focusing on emerging markets, from Abu Dhabi. He is also currently CNN's Emerging Markets Editor.
The Californian has secured numerous exclusive interviews during breaking news stories including the UAE’s Minister of Foreign Affairs on Day 1 of the Qatar 2017 Diplomatic Crisis and economic embargo against Qatar by Saudi Arabia, Bahrain, Egypt and the UAE.
Defterios was the first global broadcast journalist to enter Iran’s oil fields for a series of special reports after the 2015 P5+1 nuclear agreement.
Defterios has covered oil and gas for the past three decades and has been recognized for his analysis of the sector.
He was nominated and awarded for the Abdullah Bin Hamad Al-Attiyah International Foundation prize for the Advancement of Energy Journalism in 2017. He also became a member of the "Energy Elders" the same year.
Defterios has chaired leading global summits and forums for the past two decades including: World Economic Forum, OPEC Seminar, Atlantic Council Energy Summit, Gulf Intelligence Energy Forum, U.A.E. Government Summit, U.S.-Saudi Arabia Investment Summit, Islamic Development Bank Annual Meetings, International Monetary Fund Round table, Africa Global Business Forum and St. Petersburg International Economic Forum.
Defterios married Manuela Mirkos, at the time an employee of The New York Times, in a Greek Orthodox ceremony on the island of Sifnos in 2002. He lives in Dubai, United Arab Emirates, and reports to CNN on a regular basis from their London offices.
- "John K. Defterios". World Economic Forum. Archived from the original on 28 January 2012. Retrieved 5 August 2011.
- "Marketplace Middle East' Defterios: CNN maintains amazing entrepreneurial spirit". Free Library. Retrieved 10 October 2011.
- "John Defterios". CNN.com. Retrieved 5 August 2011.
- "John Defterios". Bloomberg Businessweek. Retrieved 5 August 2011.
- Flanagan, Ben (24 November 2011). "Anchorman rises to the challenge". The National. Retrieved 27 November 2011.
- "WEDDINGS; Manuela Mirkos, John Defterios". The New York Times. 25 August 2002. Retrieved 5 August 2011.