Maharaja Ranbir Singh was born in August, 1830 at Ramgarh. His father Maharaja Gulab Singh bestowed the Raj Gaddi of J & K State on him in the year 1856, and also appointed him as Sole Trustee of the Dharmarth Trust.

Maharaja Ranbir Singh was a great patron of learning. He contributed funds for the establishment of the Punjab University and became its first Fellow. He established the Research and Translation Bureau in J & K State, set up many pathshallas and modern schools in the state and patronized scholars. He also collected a large number of Sanskrit, Persian and Bodhi manuscripts. He introduced Dogri in official communication and even issued firmans in this language.

Maharaja Ranbir Singh built the temples in Jammu city for worship and for imparting religious education. Shri Raghunath Ji Temple complex was of personal interest to him.

Being a great social reformer, Maharaja Ranbir Singh introduced reforms in administration, the Judiciary and revenue laws. It was he who compiled the Ranbir Penal Code, which exists even today and is still applicable with some amendments. He also set up a fund to help widows and indigent girls and women in the state.

Maharaja Ranbir Singh administered the Dharmarth Trust as per the direction of his father and augmented the trust funds with further contribution to the tune of Rs. 30 lacs in the year 1884. He promulgated Ain-I-Dharmarth for the management of the Trust in a religious and sacred manner.