Born in Alwar, Rajasthan in the year 1927 into the illustrious Dagar family, Ustad Rahim Fahimuddin Dagar was the son of Padma Bhushan Ustad Allabande Rahimuddin Khan Dagar who passed away in 1975. Initiated into the art of dhrupad at the age of five by his uncle Ustad Nasiruddin Khan Dagar, he received musical education for a period of 35 years from his father and family elders. He studied Rudra Veena from his uncle Ustad Ziauddin Khan Dagar for twelve years. He also took occasional lessons from his other uncles Ustad Hussainuddin Khan Dagar (better known as Tansen Pandey) and Ustad Imamuddin Khan Dagar. He learnt Sanskrit from his father and Pt. Giridharilal Shastri.
Ustad Rahim Fahimuddin Khan Dagar was known not only for the power and spontaneity of his alaap, but also for his rich repertoire of compositions, some of which are believed to date back to the 12th and 13th centuries. As a person, Ustadji was a man of simple and sober habits and temperamentally averse to publicity. It was only the quality of his music that took him to many countries like the USA, France, Germany and Italy for performances before select audiences. His recordings have been released in Switzerland, Germany and Italy.
Ustad Rahim Fahimuddin Khan Dagar was honoured with numerous awards, prominent among them being Sangeet Ratan (1956), Sangeet Natak Akademi Award (1993-94), Dhrupad Ratan(1993-94), Sahitya Kala Parishad (1996) , Indira Gandhi Fellowship (1997), Ustad Hafiz Ali Khan Award (1997), Mewar Foundation Award (2002), Maharaja Sawai Ishwari Singh Award (2002), Kalidas Award (2002), Bihar Dhrupad Ratan (2002), Rajasthan Sangeet Natak Akademi Award (2003) , Sangeet Bhusan (2003), Shama Indian Cultural Society Award (2004), Lifetime Achievement Award (2005) by North American Dhrupad Association, Lifetime Achievement Award, by Govt. of Delhi (2007), Padma Bhushan (2008), Sangeet Natak Akademi Ratna Purashkar (2010) and the Ustad Mushtaq Ali Khan Lifetime Achievement Award (2011).
Ustadji, who was also associated with ITC SRA in the early days of the Academy passed away on 27th July 2011.