Nott-Bower was the son of William Nott-Bower, then Chief Constable of Liverpool and later Commissioner of the City of London Police. He was educated at Tonbridge School and joined the Indian Police Service by competitive examination in 1911. He was posted to the United Provinces and served there until 1921, when he returned to England to work at the India Office in London. On 21 June 1918 he was commissioned a Second Lieutenant in the Indian Army Reserve of Officers, he resigned the commission in 1922. In 1923 he returned to the United Provinces as a Superintendent. He commanded successively Allahabad, Lucknow and Bareilly districts, and also served in the Criminal Investigation Department. In the 1949 King's Birthday Honours he was awarded the King's Police Medal (KPM) for bravery after he confronted two armed terrorists on 27 February 1931, after they had shot him in the arm. One of the terrorists, who was one of the most wanted men in India, was shot dead and the other arrested.
On 29 June 1933, Nott-Bower joined the Metropolitan Police as Chief Constable (deputy commander) of No.1 District (West End, Wandsworth and Hammersmith). On 1 December 1933 he was promoted to Deputy Assistant Commissioner in command of the district. On 23 July 1937 he was made a Commander of the Royal Victorian Order (CVO).
On 1 September 1940, he was appointed Assistant Commissioner "A", in charge of administration and uniformed policing. From 1945 to 1946 he was seconded to Austria as Inspector-General of the Public Safety Branch of the Allied Control Commission, and later as Director of the Internal Affairs Division of the Commission. On his return he was promoted to Deputy Commissioner. He was made an Officer of the Order of St John on 24 June 1949 and was knighted in the King's Birthday Honours of 8 June 1950.
In the 1953 Coronation honours he was raised to Knight Commander of the Royal Victorian Order (KCVO). On 13 August 1953, Nott-Bower was appointed Commissioner. Although he had been a popular and energetic Assistant and Deputy Commissioner, he was regarded as a somewhat lacklustre Commissioner.
In his book of 1955 (Against the Law) Peter Wildeblood refers to Nott-Bower's role in the 'Great Purge' quoting an article written by Donald Horne for the Sydney Morning Telegraph printed on October 25th, 1953.
"The plan originated under strong United States advice to Britain to weed out homosexuals - as hopeless security risks - from important Government jobs. One of the Yard's top-rankers, Commander E. A. Cole, recently spent three months in America consulting with FBI officials in putting finishing touches to the plan. But the plan was extended as a war on all vice when Sir John Nott-Bower took over as the new Commissioner at Scotland Yard in August. Sir John swore he would rip the cover off all London's filth spots.... Under laxer police methods before the US-inspired plan began, and before Sir John moved into the top job at the Yard as a man with a mission, Montagu(Baron Montagu Beaulieu) and his film-director friend Kenneth Hume might never have been charged with grave offences against Boy Scouts.... Sir John swung into action on a nation-wide scale. He enlisted the support of local police throughout England to step up the number of arrests for homosexual offences. For many years past the police had turned a blind eye to male vice. They made arrests only when definite complaints were made from innocent people, or where homosexuality had encourages other crimes. They knew the names of thousands of perverts - many of high social position and some world famous - but they took no action. Now, meeting Sir John's demands, they are making it a priority job to increase the number of arrests.... The Special Branch began compiling a "Black Book" of known perverts in influential Government jobs after the disappearance of the diplomats Donald Maclean and Guy Burgess, who were known to have pervert associates. Now comes the difficult task of side-tracking these men into less important jobs - or putting them behind bars."
He introduced few reforms or innovations. He did set up the Research and Planning Branch and the Metropolitan and Provincial Regional Crime Squad and centralised traffic control in response to rising private car ownership. He did little to combat the rising crime rate, however; he refused to address the outdated hardline attitudes of many senior detectives, which were becoming increasingly out of step with postwar society; and he did not support his men in their claims for better pay and conditions. Police pay fell rapidly below inflation and rates of pay in the private sector. This caused recruiting problems and the force became seriously under strength. Nott-Bower was regarded by many of his officers as a pleasant but ineffectual man. He retired in August 1958.
In April 1960, Nott-Bower became Chairman of the Auto Call Company, a fire alarm manufacturer.
Nott-Bower married Kathleen Buck in 1928. They had two sons and a daughter.