After Bhai Gurdas Singh ji left the world for Sach Khand, their younger brother Giani Bhai Sant Singh ji was honored with the leadership of Damdami Taksal. Giani ji was the youngest son of Giani Soorat Singh ji. Giani ji was taught Gurbmat Vidiya by his father and elder brother, previous Jathedars of Damdami Taksal. From 1790 AD Giani ji performed Katha of the daily Hukamnama at Sri Harmandir Sahib. Other Gursikhs would partake in Gurmat Vidiya while Giani ji would be doing katha, as there would be five Maharaj Sri Guru Granth Sahib ji's Saroops parkash (installed).
Giani ji had the honour of teaching the famous Sikh poets Kavi Bhai Santokh Singh ji and Kavi Bhai Megh Singh ji. Giani ji was a great scholar, a true worshiper of Akal Purkh, and an enlightened Gursikh. They had great knowledge of the Sanskrit and Brij languages. Giani ji would perform katha with great splendour and spirit.
One day Maharaja Ranjit Singh after hearing the daily Katha of Giani ji thought of testing him, the Maharaja knew that Giani performed Katha daily and never missed this Seva. He sent two of mesangers requesting the company of Giani ji to meet the Maharaja. Giani ji respectfully sat the two down and served them food. After a while Maharaja Ranjit Singh sent another two messengers, as Giani ji still hadn't arrived. Giani ji treated the second two just as they did the first two. It had come the time to perform Katha at Sri Harmandir Sahib, Giani ji took these four messengers with them to Sri Harimandir Sahib. With Giani ji still not arriving at Maharaja Ranjit Singh's palace, the Maharaja decided to go to Darbar Sahib himself. He was impressed with the discipline of Giani ji that they didn't miss performing the daily Katha just to see him.
Giani ji as well as being the Jathedar of Damdami Taksal was the Head Granthi (Priest) of Sri Harmandir Sahib. They would always make themselves available to talk with and discuss issues with any Gursikh who would come and see them. They would also take part in the seva of cleansing the Parkarma (outer path), picking up the droppings of birds with their own hands. They would also pick up any hair and burn them as per the Rehat Maryada (Code of Conduct) of a Gursikh. Giani ji would do Seva of Sri Guru Ram Das Sahib ji's Darbar (Court) with much passion. They had such great discipline that even when one of their grandsons passed away they still didn't miss any of their daily Seva.
Maharaja Ranjit Singh once fell in battle and was injured. It was Giani ji who picked him up on their back and brought him back to the fort. For the rest of his life, Maharaja Ranjit Singh didn't forget this great deed. Giani ji was the teacher of Shazade Kanwar Naunihal Singh. They also oversaw the Seva of Maharaja Ranjit Singh, when Sri Harmandir Sahib was covered in gold, they ensured that this was completed with the greatest respect for Guru Sahib Ji.
Giani ji persuaded Bhai Desa Singh to complete the seva of covering the two Nishan Sahibs at Gurdwara Baba Atal Rai in gold. Giani ji had great discipline and were complete in Seva and Simran (meditation). In the words of Kavi Megh Singh, Giani ji was a great scholar and a strong athletic person. They left the world for Sach Khand in the year 1832 AD. They left three sons: Bhai Deva Singh, Bhai Gurmukh Singh and Bhai Jodh Singh. Bhai Gurmukh Singh became the head granthi at Darbar Sahib after them.