Driving distance from Washington, DC to Knoxville, TN. The total driving distance from Washington, DC to Knoxville, TN is 486 miles or 782 kilometers. Your trip begins in Washington, District of Columbia. It ends in Knoxville, Tennessee. If you are planning a road trip, you might also want to calculate the total driving time from Washington, DC to Knoxville, TN so you can see when you'll arrive at your destination.