I don't like to contradict Su.Ki and this may well be a different in British and U.S. usage. I'm a U.S. native speaker. "On foot" sounds perfectly correct and perfectly natural to me. Since "on foot" is correct and natural everywhere, it is obviously the better choice. Nevertheless, I think "by foot" is acceptable in the U.S. For example, consider http://www.bostonbyfoot.org "Boston By Foot," an organization which presents walking tours of Boston. Google finds me so many examples that I have to think that if it ever was incorrect, it is now accepted. For example: A 2010 book, "Slow Journeys: The Pleasures of Travelling by Foot." A 2007 book, "The Blue Ridge Parkway by Foot: A Park Ranger's Memoir." "Trekking, as described here, means travel by foot for many days. --"Trekking Nepal," 2010 "Automobile reconnaissance was employed to map areas available from roads, while reconnoitering by foot was used for mapping types in areas not visible from roads,"--"The Anthracite Forest Region," 1948 "He'll come back and find out that the master went by foot . . . blackguardl”--"The Eternal Husband and Other Stories," Fyodor Doestoevsky, translated by Richard Pevear and Larissa Volokhonsky, 1997 "Bretz's earliest investigation was all by foot—he could not at first afford a car...", "Cataclysms on the Columbia: The Great Missoula Floods", 2009

When you get from one place to another by any mode of TRANSPORTATION, you use "BY". For example: I plan to go to church by car. When you WALK from one place to another, you use "ON" and not "BY". For example: I plan to go to church on foot, not by car. Hope this helps! ^_^

'By foot' is a very common mistake made by foreign learners. Don't use this phrase - it doesn't exist in correct English. Anyone who told you that you could say 'by foot' is wrong. The correct expression is 'on foot'. By car, by bus, by bike, by plane, but ON FOOT.

Both grammatically correct, but I wouldn't suggest using either of them in conversation. You travel by car, you walk on foot. By is a method of transportation. By car, by plane, by coat. You literally walk on your feet. So you can say "I went home on foot." But most people would just say "I walked home."

As others have said, "by" is generally used for methods of transportation. "foot" isn't a method of transportation. I would say "by walking" or "on foot", but I never say "by foot". It seems really weird Some people might say that, but i don't like it You can get there in 10 minutes by walking. You can get there in 10 minutes on foot.