Born as William Bramwell Booth in Halifax, Yorkshire, England, the oldest child born to William Booth and Catherine Mumford, he had two brothers and five sisters, including Evangeline Booth, Catherine Booth-Clibborn, Emma Booth and Ballington Booth. The Booth family regularly moved from place to place as William Booth's ministry necessitated until the family finally settled in London in 1865. Bramwell Booth was involved in The Salvation Army right from its origins as the obscure Christian Mission, established in Whitechapel in 1865, into an international organization with numerous and varied social activities. He was educated at home, briefly at a preparatory school and at the City of London School, where he was bullied.

Known to his family as 'Willie', as a youth he suffered poor health and had a slight hearing loss. In 1870, aged just 14, Bramwell Booth started to help in the management of his father's Christian Mission and in the cheap food kitchens set up in its early days. He had intended to study medicine and had a fear of public speaking, but despite these obstacles he became William Booth's amanuensis, adviser and administrator. He became an active full-time collaborator with his father in 1874, and an officer when the Christian Mission became The Salvation Army in 1878.

The name The Salvation Army developed from an incident in May 1878. William Booth was dictating a letter to his secretary George Scott Railton and said, "We are a volunteer army." Bramwell Booth, heard his father and said, "Volunteer, I'm no volunteer, I'm a regular!" Railton was instructed to cross out the word "volunteer" and substitute the word "salvation".

In 1881, General William Booth appointed Bramwell as his Chief of the Staff of The Salvation Army. Bramwell would hold this title until his father's death, when he himself was named General in his father's will. In 1885 Bramwell was involved with William Thomas Stead in an attempt to publicize the prostitution of young girls. The lurid revelations of how thirteen-year-old Eliza Armstrong was sold for £5 resulted in the 1885 Criminal Law Amendment Act, which raised the age of consent to sixteen years. After the revelations, Booth, Stead, and Rebecca Jarrett, a converted brothel-keeper who assisted them, were arrested on several charges. Booth was acquitted but the others served short prison terms.

On 12 October 1882 Bramwell married Captain Florence Eleanor Soper, the eldest daughter of Dr Soper, a medical practitioner of Blaina, Monmouthshire. The congregation at Clapton Congress Hall were charged one shilling each for admission to the ceremony. She had joined The Salvation Army in 1880 and worked in France with Bramwell's sister Catherine Booth. After her marriage she took charge of the women's social work. All of their seven children (five daughters and two sons) became active workers in the army. Their eldest child was Commissioner Catherine Bramwell-Booth.

In his will William Booth appointed Bramwell his successor as General. Bramwell Booth succeeded to that position on the death of his father in 1912. Like his father, Bramwell Booth ruled autocratically, and expected complete obedience. However, what officers had tolerated from William Booth, by now known as ‘The Founder’, they would not tolerate from Bramwell. Like his father before him, Bramwell would not tolerate any perceived insubordination and he summarily retired Salvation Army officers with little reason. It was claimed that he appointed his own children to posts for which others were better qualified. This system was inherited from his father, who similarly appointed his own children to such posts. This lead to accusations that The Salvation Army was a Booth family-business. Discontent simmered among Salvation Army senior officers, including some of Bramwell's own brothers and sisters. In his final years as General he increasingly gave control of The Salvation Army to his wife, Florence Booth, who was given power of attorney when he was away travelling. She had been the Army's ‘First Lady’ since his death of his mother Catherine Booth in 1890, and had started several Army organizations including the Home League, Girl Guards, and League of Mercy.

The early years of Bramwell Booth's Generalship were complicated by World War I, which threatened the international nature of The Salvation Army, with Salvationists in both Germany and Great Britain. However, he was able to steer a course that offended neither the Germans nor outraged British public opinion, saying in his Christmas message of 1915, "Every land is my fatherland, for all lands are my Father's.". As the years passed the Army's senior officers, including Bramwell's sister Evangeline Booth and his former brother-in-law Frederick Booth-Tucker, began to question his leadership. In May 1928 Bramwell's health began to deteriorate, and by September he was suffering from insomnia and depression. His poor health offered those in the Army who were dissatisfied with his leadership an opportunity to act, and 8 January 1929 the High Council of The Salvation Army asked the General to resign due to his ill health, which, they said, was hampering him in the performance of his duties and decisions. He refused to resign, believing that his health would soon be fully recovered, and on 13 February 1929 the High Council voted by 52 votes to 5 that Bramwell's term of office as General should now end. Booth was succeeded in the election of Edward Higgins, his Chief of the Staff.

General Bramwell Booth then took the High Council to court, which lost him a lot of respect; he also lost the court case. His sister, Evangeline Booth later succeeded General Higgins to serve as the third General of The Salvation Army. Henceforth the General of The Salvation Army would be elected by the High Council.

On 29 April 1929 the now former General Bramwell Booth received a letter from Prime Minister Stanley Baldwin stating that King George V had appointed him a member of the Order of the Companions of Honour.

On 16 June 1929 his family was summoned to his bedside, and on that Sunday evening General Bramwell Booth died (or was Promoted to Glory) at his home, The Homestead, Hadley Wood, near Barnet, Hertfordshire. For the Friday and Saturday following his death Bramwell Booth's body lay in state at The Salvation Army's Congress Hall. On the Saturday evening 10,000 Salvationists and friends filled the Royal Albert Hall to bid farewell to their beloved former General.

General Bramwell Booth was buried near his parents at Abney Park Cemetery, Stoke Newington, London. Huge crowds attended his funeral. He was commemorated by the Bramwell Booth Memorial Hall, Queen Victoria Street, London.