Bhai Mani Singh was born on the 10th of March, 1644 CE, at village Alipur, in district Muzaffargarh. He came for an audience with Guru Har Rai to Kiratpur with his father Mai Das for the first time and stayed back to serve the Guru-ghar. He was married at fifteen to Bibi Sito, daughter of Bhai Lakhi Rai. After the battle of Nadaun in 1690 CE, Guru Gobind Singh entrusted him the duties of Diwan. At the time of leaving Anandpur on the night of December 20-21, 1704 CE, the Guru entrusted him to take the Guru Mahal to a safe place. In May, 1705 CE, at the call of the Guru he reached Talwandi Sabo where he helped the tenth Master in compiling the final recension of Guru Granth Sahib and prepare some copies of it for distribution amongst the Sikhs. In 1708 CE, Mata Sunder Kaur sent him to Amritsar to take charge of Harmandar Sahib.

In 1735 CE, Zakria Khan, the Governor of Lahore, ordered village headmen and landlords to finish Sikhs of their areas. He also appointed Diwan Lakhpat Rai, an enemy of the Sikhs, the administrator of Amritsar and Qazi Abdul Razak as the police chief. One day, the Governor asked them, 'What is the reason that no matter what the number of Sikhs we kill more are created ?" The Qazi replied, "Their Guru had put the elixir of life in the pool at Harmandar Sahib. Whosoever bathes in that pool, gains eternal life." Hearing this, the Governor ordered the filling up of the pool with sand and turned Bhai Mani Singh out from the service of Harmandir Sahib.

Having been turned out from Harmandir Sahib, Bhai Mani Singh took up residence at the Sultanwind's well. one evening Qazi Abdul Razak came to Bhai Mani Singh and said, "My children are very ill. Medicines of local physicians and doctors are having no effect. Children wake up with nightmares." Bhai Mani Singh went with him to his house. He sprinkled water from the pool of Harmandar Sahib over the children and said to them, "Be not afraid during the night." As the Lord would have it, the nightmares stopped. Qazi Abdul Razak stopped silting up the pool.

With the help of the Qazi, Bhai Mani Singh got permission from the Governor to allow Sikhs to have free access to Harmandar Sahib for ten days on the occasion of Diwali of 1737 CE, on the condition to pay tax of Rupees five thousand and so he wrote letters to invite the Sikhs. The Governor and Diwan Lakhpat Rai secretly planned to kill the Sikhs coming for the pilgrimage. Bhai Mani Singh came to know of their plan in time. He sent messages to Sikhs not to come and so no fair was held.

The Governor called Bhai Mani Singh to Lahore and demanded the tax money. Bhai Mani Singh said, "What for should I pay the money when the fair was not held ?" Then the Governor asked Bhai Mani Singh to embrace Islam. He refused. Qazi Abdul Razak ordered that Bhai Mani Singh be cut joint by joint. On the 14th June, 1738 CE, he was martyred at Nakhaas Chowk by cutting him joint by joint.