Gertten worked as a journalist for newspapers, radio and television in Africa, Latin America, Asia and Europe during the 1980s and 1990s. In 1995 he published the travel book Ung man söker världen (Young man looking for the World) through the publisher Gong Gong förlag. He wrote for the newspaper Arbetet from 1990 until it ceased publication in 2000 and for Kvällsposten in 2001-2003. He has also been the producer of documentaries and entertainment shows for the Swedish television channels SVT, TV 4 and TV 3.
In 2009, Gertten's production company WG Film was sued for defamation by Dole Food Company after the US screening of Bananas!*, a documentary film about a conflict between Dole and banana plantation workers in Nicaragua over alleged cases of sterility caused by the pesticide DBCP. The court ruled in favor of the production company, and the lawsuit became the subject of Gertten's 2011 documentary Big Boys Gone Bananas!*.
As director and producer
- 2015 - BIKES vs CARS
- 2011 - Big Boys Gone Bananas!*
- 2009 - Bananas!*
- 2005 - Sossen, arkitekten och det skruvade huset (The Socialist, the Architect, and the Twisted Tower)
- 2005 - An ordinary family"
- 2003 - Bye Bye Malmö (Just a piece of steel)
- 2002 - Poesigeneralen (The Poetry General)
- 2002 - Vägen tillbaka - Blådårar 2 (The way back, True blue 2)
- 2001 - Resa med Siluett (Travel with Siloutte)
- 2001 - Mordet på en tidning (The death of a working man's newspaper)
- 2000 - The great bridge] (short film)
- 2000 - Gå på vatten (Walking on water)
- 1998 - Blådårar (True Blue)
- 2008 - "Burma VJ", Anders Østergaard
- 2008 - "Final Image", Andrés Habbeger
- 2007 - "The Leftovers", Kerstin Übelacker & Michael Cavanagh
- 2006 - Milkbar, Terese Mörnvik & Ewa Einhorn
- 2006 - Thin Ice (Tunn Is), (2006) Håkan Berthas
- 2006 - Belfast Girls, Malin Andersson
- 2003 - Love Boat, short film, Anna Norberg
- 2002 - Boogie Woogie Pappa, short film, Erik Bäfving
- 1998 - Sambafotboll, Lars Westman & Fredrik Ekelund
- Mattias Oscarsson (20 February 2012). "Filmkriget". Sydsvenskan (in Swedish). Retrieved 24 April 2013.
- "Filmen "Bananas" vann Dole-rättegång". Svenska Dagbladet (in Swedish). 29 November 2010. Retrieved 2 December 2011.
- Sigander, Miranda (2 December 2011). "Revansch på Sundance för Gertten". Dagens Nyheter (in Swedish). Retrieved 2 December 2011.