Designed by engineer John Rennie, construction of the canal started in 1794. The canal opened in 1810, with some impressive engineering feats, including a number of aqueducts, pumping stations and locks. The Great Western Railway relieved the canal of much of its traffic when it opened, and in 1846 the GWR Company took over the running of the canal, levying high tolls until the canal was hardly used.
In the 1950s large portions of the canal were closed because of poor lock maintenance, and in 1956 the Kennet & Avon Canal Trust successfully petitioned against its legal closure. In 1963 the newly formed British Waterways took over the canal and began restoration work. In 1990 Queen Elizabeth II reopened the canal but, because of problems with pumping, the canal could be used only part-time until August 1, 1996 when new backpumps were installed at the Caen Hill flight of 29 locks at Devizes. The pumps raise 300,000 gallons of water each hour 235 feet. In October 1995 the Heritage Lottery Fund granted the project £25 million towards further structural improvements and maintenance.
The canal today is a popular heritage tourism destination, especially around the city of Bath, a popular cultural and historical tourist destination. The canal is also important for wildlife conservation.