Towell grew up in a large family in rural Ontario, attending local schools. At college, he studied visual arts at York University in Toronto, where his interest in photography first began. In 1976 Towell volunteered to work in Calcutta, India, where he became interested in questions about the distribution of wealth and issues of land and landlessness. 
Returning to Canada, Towell taught folk music and wrote poetry. He became a freelance photographer in 1984. His early work included projects on the Contra war in Nicaragua, the civil war in El Salvador, relatives of the disappeared in Guatemala, and American Vietnam War veterans who worked to rebuild Vietnam. His first magazine essay looked at the ecological damages from the Exxon Valdez oil spill.
In 1988, Towell joined the Magnum photo agency, becoming the first Canadian associated with the group. He has had picture essays published in The New York Times, Life, Rolling Stone, and other magazines. His work has included documentation of the Palestinian-Israeli conflict, Mennonite migrant workers in Mexico, and a personal project on his family's farm in southern Ontario.
He always works with traditional film, eschewing digital options: “Black and white is still the poetic form of photography. Digital is for the moment; black and white is an investment of time and love.” He has also worked with panoramic cameras, which allow him to shoot the “landscapes of destruction”—looking at human beings and their place in the landscape.
Towell’s bibliography includes books of photographs, poetry, and oral history. He has also recorded several audio CDs of original poetry and songs. Towell lives in rural Lambton County Ontario and sharecrops a 75-acre farm with his wife Ann and their four children.
- Burning Cadillacs (1983)
- Gifts of War (1988)
- Somoza's Last Stand (1990)
- The Prison Poems of Ho Chi Minh (1992)
- House on Ninth Street (1994)
- El Salvador (1997)
- Then Palestine (1999)
- The Mennonites (2000)
- No Man's Land (2005)
- In the Wake of Katrina (2006)
- The World From My Front Porch (2008)
- The Cardboard House: MSF Peru - Action on Aids. Trolley Books. 2008. ISBN 978-1-904563-71-6.
- Ruins: Afghanistan (2009)
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- 1991: Silver Medal, Canadian National Awards
- 1991: W. Eugene Smith Foundation Award
- 1991/93: Gold Medal, Western Canada Magazine Awards
- 1993: 1st Prize in category ‘Daily Life Stories’, World Press Photo
- 1994: Premier Photo of the Year, World Press Photo
- ‘General News Stories’
- 1994: World Press Photo, 1st Prize in category ‘Daily Life Stories’, 1st Prize in category
- 1994: Picture of the Year, Canon Photo Essay Award
- 1994/95: Gold Medal, Canadian National Awards
- 1995: Ernst Haas Foundation Award
- 1996: El Mundo Award
- 1996: Oskar Barnack Award
- 1997: Golden Light (Best Monograph Award)
- 1998: Society of Publication Designers, Merit Award, "The New York Times Magazine"
- 1998: Society of Publication Designers, Magazine of the Year,"The New York Times"
- 1998: Overseas Press Club, New York, Citation of Excellence
- 1998: ‘Pictoral’ Prize, Pictures of the Year Foundation, University of Missouri
- 1998: 1st Prize, Alfred Eisenstaedt Award
- 1999: Picture Of the Year (Best Use of Photography in Books)
- 1999: Roloff Beny Book Award
- 1999: Hasselblad Foundation Award
- 2000: Photo-eye Award, Citation of Excellence
- 2000: Society for News Design Award, La Nacion
- 2006: Photo District News Photo Annual: One of the year’s best projects
- 2007: Alicia Patterson Award (USA, Finalist)
- 2007: Achievement In Filmmaking Award, New York Independent Film And Video Festival
- 2008: One of the year’s best pictures, Photo District News
- 2009: The World From My Front Porch, one of “50 Best” photo books of the year. Festival Of The Photograph. Charlottesville, VA
- 2009: The World From My Front Porch, And/or Photography Book Award(Kraszna-Krausz Foundation, UK- shortlisted)
- 2009: The World From My Front Porch, Top ten best photo books of 2008, Photo-Eye
- 1991: Le Mois de la Photo - Maison de la Culture Plateau, Montreal, Quebec, Canada
- 1994: Carnets de Voyage - Canadian Museum of Contemporary Photography
- 1994: Retrospective - Nieuwekerk, the Netherlands
- 1997: Circulo de Bellas Artes, Madrid, Spain
- 1997: Noorderlicht Photo Festival, Groningen, Netherlands
- 2001: Canadian Museum of Contemporary Photography, Ottawa, Ontario, Canada
- 2001: National Portrait Gallery, Edinburgh, UK
- 2005: No Man's Land - Fondation Henri Cartier-Bresson, Paris, France
- 2006: FOAM, Amsterdam, Netherlands
- 2008: George Eastman House, Rochester, New York
- 2012: Royal Ontario Museum, Toronto, Ontario, Canada
- "Larry Towell biography". Magnum Photos. Retrieved 2006-12-28.
- "Larry Towell biography". Bulger Gallery. Retrieved 2011-01-12.
- "Larry Towell article". Walrus Magazine. Retrieved 2011-01-12.
- "Larry Towell: The World From My Front Porch at Eastman House Feb. 16 through June 15". George Eastman House. Archived from the original on 2008-06-01. Retrieved 2008-04-27.
- "Larry Towell and Donovan Wylie: Afghanistan". CONTACT Photography Festival. Archived from the original on 2014-10-11. Retrieved 2014-10-07.