Born in Chicago, Webster grew up in Chicago's North Shore community of Wilmette, Illinois. He graduated from New Trier High School and Kenyon College, finishing with a BA in English in 1981, and then went on to attend Middlebury College's Breadloaf School of English for MFA graduate school. He then moved to New York City, where he wrote for several magazines, many with the Conde Nast Corporation, where he was soon employed. In 1986, working with friends, he co-founded Southern magazine, which was purchased by Time, Inc. in 1989. After that, he spent several years as senior editor at Outside magazine before going to write full-time.
In 1996—following a cover story he wrote in The New York Times Magazine about global land-mine proliferation—he co-founded Physicians Against Landmines/Center for International Rehabilitation (CIR). An international, non-governmental humanitarian organization, CIR sponsors field hospitals, wheelchair and prosthetics programs, plus prosthetics-fabrication training and disability advocacy in post-conflict nations worldwide. In 1997, as an early member of the International Campaign to Ban Landmines, CIR was a co-recipient of the Nobel Peace Prize. In 2006, working with the United Nations Special Rapporteur for Disabilities, CIR was central to the UN’s Convention on the Rights of Persons with Disabilities, the most-rapidly ratified UN Convention to ever gain approval by the UN General Assembly. He currently serves as CIR's vice-chairman. In 2005, he ground-reported and co-authored the United Nations report on destruction and disabilities created around the Indian Ocean basin by the 2004 Banda Aceh Tsunami.
In 2007, he was co-founder and became President of Tidene/USA: the U.S. arm of the non-governmental humanitarian organization Tidene (which he also co-founded in 2006). Originally a France-based project with offices developed in Washington DC, and Agadez, Niger, Tidene builds water wells for humans, livestock, and agricultural cultivation, as well as schools and hospitals for the Tuareg people of Niger: the poorest and driest country on earth. Since 2007, 231 wells, a school, and a dispensary hospital have been created across an area the size of Germany. Together, these facilities help the Sahara's nomadic people survive and prosper (the ultimate goal is 400 wells). Funding has come from the U.S. Congress—through the US African Development Foundation, an arm of the US Congress and USAID—plus a devoted conglomerate of French philanthropists and wine producers. In 2014, Tidene/USA was absorbed into a larger organization, Les Puits du Desert/Tidene.
He wrote "Traveling the Long Road to Freedom, One Step at a Time," which was published in Smithsonian magazine; this article was recently used in the English language and literature pre-release material (AQA).
In 2006 and 2007, he was co-leader of the expedition Running the Sahara: an on-foot crossing of North Africa from the Atlantic Ocean beach in Senegal to the beach at the Suez in Egypt. The expedition was filmed and edited into a documentary film, Running the Sahara, narrated by Matt Damon and released in 2007 with the logistics support of Sam Rutherford at www.prepare2go.com. The Running the Sahara project began in Senegal, went through Mauritania, Mali, Niger and Libya, before culminating in Egypt. Runners included Ray Zahab and Kevin Lin.
In February 2009, he became a graduate of Gruppo Storico Romano, the Roman Coliseum's Gladiator School, becoming a recognized gladiator with the organization's 11th Legion.
In July and August 2010, he and photographer Ron Haviv traveled to Madre de Dios Region in southeast Peru for the Amazon Aid Foundation. There they documented the environmental destruction of the upper-Amazon basin rainforest by illegal gold mining, a practice that has increased exponentially due to a recent leap in gold prices. A documentary-film team followed their investigation. The result is Amazon Gold, a multi-award-winning theatrical documentary film narrated by Academy Award winners Sissy Spacek and Herbie Hancock.
His next film is fictional and is loosely based in truth. It is currently being negotiated.
On August 14, 2014, Webster was charged with driving under the influence after he caused a fatal head on collision that killed 75-year-old Wayne Thomas White Sr. on Afton Mountain's route 250 near Waynesboro, Virginia. In October, the commonwealth's attorney added a charge of involuntary manslaughter, and in December he was formally indicted.
On February 18, 2015, Webster pleaded guilty to involuntary manslaughter.