Barnes Wallis was born in Ripley, Derbyshire to Charles William George Robinson Wallis (1859–1945) and his wife Edith Eyre Wallis née Ashby (1859–1911). He was educated at Christ's Hospital in Horsham and Haberdashers' Aske's Hatcham Boys' Grammar School in southeast London, leaving school at seventeen to start work in January 1905 at Thames Engineering Works at Blackheath, southeast London. He subsequently changed his apprenticeship to J. Samuel White's, the shipbuilders based at Cowes on the Isle of Wight. He originally trained as a marine engineer and in 1922 he took a degree in engineering via the University of London External Programme.
He left J. Samuel White's in 1913 when an opportunity arose for him to work on airship design and then aircraft design. He worked for Vickers – later part of Vickers-Armstrongs and then part of the British Aircraft Corporation – until his retirement in 1971.
His many achievements include the first use of geodetic (also known as geodesic) design in engineering and in the gasbag wiring of Vickers' R100 in 1930, which, at the time, was the largest airship ever designed. He also pioneered, along with John Edwin Temple, the use of light alloy and production engineering in the structural design of the R100. Nevil Shute Norway was the chief calculator for the project, responsible for calculating the stresses on the frame.
Despite a better-than-expected performance and a successful return flight to Canada in 1930, the R100 was broken up following the crash in northern France of its "sister" ship, the R101 (which was designed and built by a team from the Government's Air Ministry). The later destruction of the Hindenburg led to the abandonment of airships as a mode of mass transport.
By the time of the R101 crash, Wallis had moved to the Vickers aircraft factory at the Brooklands motor circuit and aerodrome between Byfleet and Weybridge in Surrey. The pre-war aircraft designs of Rex Pierson, the Wellesley, the Wellington and the later Warwick and Windsor all employed Wallis's geodetic design in the fuselage and wing structures.