On January 19, 1971, two oil tankers owned by Standard Oil Company, the Arizona Standard and California Standard, collided in San Francisco Bay, creating an enormous oil spill. After seeing the damage caused, John Francis joked with a friend about never riding in a car again. The following year, a neighbor of Francis' died suddenly. Faced with a new sense of the uncertainty of life, Francis decided to act immediately and for the next 22 years refused to ride in motorized vehicles. Francis describes himself as having had an over-inflated sense of self-importance at this time, and says that he initially expected other people to follow his example and also forgo automobiles and other powered vehicles.

As Francis traveled about on foot, people would sometimes stop to talk about what he was doing, and he often found himself arguing with them, as well as with friends and acquaintances, about his decision to go on foot. On his birthday in 1973, Francis decided to stop speaking as a gift to his community, to not argue for one day and instead listen to what others had to say. He found this so valuable that he continued to be silent the next day. This continued and he ended up not speaking for 17 years, with the exception of a phone call to his mother after 10 years of silence. During this time, he communicated by writing and gestures, and also expressed himself by playing the banjo. He ended his vow of silence on Earth Day in 1990. The following day, while in Washington, D.C. he was struck by a car. He managed to convince the ambulance crew to allow him to walk to the hospital.

While he was silent, he completed three college degrees, culminating in a Ph.D. in Land Management from the University of Wisconsin—Madison. He walked to Ashland, Oregon to enroll in Southern Oregon University, and completed a B.A. there in a two-year program. Next, he walked to the state of Washington and built a boat, contacting the University of Montana and informing them that he'd like to enroll in a master's degree program in about two years. He walked and sailed to Montana, and completed his degree there. With little money, he audited classes but professors tracked his grades, and when funds became available to pay for the classes he had taken, they were put on his transcript for credit. As is common with graduate students, Francis taught classes while studying for his master's degree.

Francis then walked to Wisconsin, where he took up his doctoral studies, focusing on the effects of oil spills. During his studies, the Exxon Valdez disaster occurred, which brought attention to his research. After completing his degree, he walked to Washington D.C.

In 1994, Francis decided he could be a more effective environmentalist if he began to again use motorized transportation. At the border of Venezuela and Brazil, he boarded a bus.

Francis has been employed by the United States Coast Guard to work on legislation relating to management of oil spills. In 1991 he was named a United Nations Environmental Program Goodwill ambassador. In 2009 he was in Australia, walking the Great Ocean Road for a film being made by Tourism Victoria.

He is the author of Planetwalker: How to Change Your World One Step at a Time. He lives in Point Reyes Station, California with his wife and two sons.

His life story has been optioned by Universal Studios in 2006 for a movie release, with rumor of Will Smith expressing interest to play the role of John Francis.