He left his worldly life and became a bairagi sadhu or a wandering hermit and ultimately settled at Nander on the banks of river Godavari in Maharashtra. He won great fame as a sorcerer under the name of Madhodas. Thousands of people followed him. Guru Gobind Singh went to his hermitage. That time Madhodas was not there. The Guru ordered his adherents to kill a few goats of the Bairagi and cook meat there and then matter was reported to Bairagi. The Guru asked him who he was. Madhodas replied, he was Banda or Guru's slave. The Guru inquired, if he knew whom he was talking to. He said he was none other than Guru Gobind Singh. At that time Banda was 38 years old and Guru ji 42. The Guru encouraged him to resume the duties of a real Rajput. Then Guru appointed him his military lieutenant to punish the Governor of Sarhind who had killed his two youngest sons, his mother and thousands of Sikhs and Hindus. He arranged the council of advisers of Five Sikhs and assured them that Banda was Guru's nominee and deputy to organize them in order to lead an expedition against Sarhind. About the middle of September 1708 at Nander, the Guru involved Banda Singh Bahadur in the national struggle in the Punjab and to punish Wazir Khan of Sarhind and his supporters. And sent message of Guru Gobind Singh to various places to Khalsa, raised an army of the selfless Sikhs under numbers of commanders of Sikhs and attacked Sarhind in the year 1710 AD. Wazir Khan and his men were killed. Sirhind was conquered.

In Dec. the same year he faced the Mugal army in the field of Sadhoura and defeated the Mugals. First time in Indian history slavery of more than 700 years, a Sikh Raj was established at Sirhind in the heartland of the Mugal Empire in 1710 AD by Baba Banda Singh Bahadur. Again in June 1711, Bahadur Shah sent his army in the field of Behraam pur to kill Banda Singh Bahadur but got defeated. After the death of Bahadar Shah in 1712, Farakhsieyer became the next king of India. Within two years Banda Singh conquered almost east of Punjab and other nearby areas. He moved towards Himachal and conquered Bilaspur.

On receipt of the of the information of the arrival of the Sikhs in the neighbourhood, many of the inhabitants of these places deserted their homes and fled to Lahore and other places to safety their families and such property as they could remove. When Banda arrived at the Tank of Achal, about 6km to the east of Batala, and on the following day turned his attention to the town. The inhabitants shut the gates and prepared them to defend the walls, while the Shaaikh-ul-Hind himself, with his followers and inhabitants went out of the Hathi Gate to meet Banda. On reaching the road he made a bold stand, but he could ill-afford to stand against the Khalsa, and, after a short struggle, he was overpowered and slain. The followers of the Shaikh-ul-Hind were soon defeated and driven back. Under the orders of Banda, the Sikhs broke open the gates and entered the town. The college of Sayyed Muhammad Fazil-ud-Din Qadri, which was now empty, and many of palatial buildings of the town beginning with the house and mohalla of Qazi Abdul Haq, perished in the flames.

Again in 1713 he defeated the Mugal Army in the field of Sadhaura. He was enemy of the cruel rulers. After ruling 8 years, he stand-up against the terror of rulers. At the behest of Farakhsieyer, in Dec 1715 Banda Singh Bahadur, along with a few hundred sikhs, was encircled in the fort of Gurdaas Nangal. After about 8 months the fort was attacked and Banda Singh and his men were arrested. Thousands of sikhs were killed and their dead heads were loaded in number of carts. About 700 Sikhs were arrested on the way. They were brought to Delhi in the form of a big horrifying procession leading with Banda Singh in a cage over an elephant, prisoners in chains and carts with dead heads. It clearly showed that the sikhs had no right to live. In March 1716, daily 100 Sikhs were executed for 7 days at Khooni Darwaza, Delhi. Not even a young boy of 15 years, even at the requests of his mother left Sikhism but embraced Death. After 3 months, in June 1716 AD Banda Singh and his few men were executed. The Mugals were mad for knowing about the secrets of Sikh wars from Banda Singh and his few men. Before execution of Banda Singh his young son was killed with a dagger. Vibrating heart of the dead child was forced into the mouth of brave Banda Singh and he resisted. After this his eye balls were notched out, hands, feet and knee were chopped off. As if not enough with long hot tongs his flesh was pulled and was thus ultimately put to death. This was to set an example to create terror in the minds of the general public by the rulers.