Born in Mayfair, London, Curzon was the only son of Richard Curzon, 4th Earl Howe. Following family tradition, he joined the Royal Naval Reserve and by October 1907 held the rank of Commander, appointed to lead the Sussex Division of the Royal Naval Volunteer Reserve. During the First World War the RNVR was formed into the Royal Naval Division for land combat, and Curzon served as Battalion Commander of the Howe Battalion in the 2nd Brigade RND. The battalion saw action at Gallipoli in 1915, in Salonika, and across France and Belgium until it was disbanded in February 1918. He also served as aide-de-camp to King George V and, as a keen filmmaker, organised the cinematograph service for the Navy, personally filming the surrender of the German fleet at Scapa Flow.
In the 1918 General Election Curzon won the Battersea South constituency for the Conservative Party, a seat he held until 1929, when he ascended to the earldom following his father's death and took his seat in the House of Lords. He was appointed a Privy Counsellor in the 1929 Dissolution Honours. Even while serving in Parliament he had grown increasingly drawn to motor racing, and continued to champion motorsport causes in the Lords throughout the rest of his life.
Curzon made his race debut at the comparatively late age of 44 at the 1928 Irish Tourist Trophy, driving a Bugatti Type 43. His career accelerated rapidly after leaving the House of Commons. An associate of the Bentley Boys, he entered the 24 Hours of Le Mans six times between 1929 and 1935, missing only the 1933 edition. In his debut Le Mans year he drove as part of the Bentley factory team. After Bentley was acquired by Rolls-Royce in 1931 and withdrew from competition, Curzon campaigned his own cars.
At the 1930 Le Mans he drove his own Alfa Romeo 6C alongside co-driver Leslie Callingham to fifth overall and third in the 3-litre class. The following year, at the 1931 24 Hours of Le Mans, he upgraded to an Alfa Romeo 8C and won the race outright in partnership with Henry Birkin — the crowning result of his driving career.
Beyond Le Mans, Earl Howe — as he was commonly entered following succession to the title — competed in a wide variety of machinery. Time magazine credited him in the mid-1930s with owning "Europe's most elaborate" collection of racing cars. Favouring Bugatti, he won the Donington Park Trophy race in 1933 and the 1938 Grosvenor Grand Prix in Cape Town, South Africa. He claimed podium finishes in eleven other major races between 1933 and 1939 and became one of only two drivers to have competed in every running of the RAC Tourist Trophy on the Ards Circuit.
In 1937 he was seriously injured at Brooklands while challenging Prince Bira for the lead in the Campbell Trophy, driving his pale blue and silver English Racing Automobiles R8B — his personal racing colours.
In 1928, Curzon was instrumental in working with Dudley Benjafield to establish the British Racing Drivers' Club. Elected its first president at the BRDC's inaugural Annual General Meeting in 1929, he held that office until his death in 1964. He also served as vice-president of the FIA's Commission Sportive Internationale, the governing body of international motorsport.
After the Second World War — during which he returned to naval service with the rank of commodore — Curzon shifted his energies to race organisation. He helped prepare and enter cars for other drivers, including Tazio Nuvolari, and applied political pressure to open wartime airfields to motorsport. He was closely involved in organising the first British Grand Prix at Silverstone in 1948, which became a round of the inaugural Formula One World Championship in 1950, and instituted the annual BRDC International Trophy meeting at the same venue. Under his 35-year stewardship the BRDC evolved from a private dining club into one of the most prominent motor sport associations in the world.
The BRDC honours his memory with the Earl Howe Trophy, awarded annually to recognise outstanding performance in motorsport. Originally presented to the highest-placed British driver at the Indianapolis 500 or the most meritorious British performance in North American racing, the criteria were revised from 2019 to recognise excellence in historic racing.
Curzon married three times. His first wife was his first cousin Mary Curzon, whom he married in 1907; they divorced in 1937. He next married Joyce Mary Mclean Jack in 1937, divorcing in 1943, and in 1944 wed Sybil Boyter Johnson, with whom he had his third daughter, Lady Sarah Curzon, who later married Formula One driver Piers Courage.
Earl Howe died on 26 July 1964 and was succeeded by his eldest son Edward.