Lam Dorji was born in Haa. He graduated from the Indian Military Academy in Dehradun, India, at the end of 1954, and completed a post-training attachment with a range of Indian Army units and instructional schools. In March 1959, he received his first assignment, to establish the RBA training center in Wangduephodrang. He also represented the Armed Forces at the National Assembly. In 1962, during the Indo-China war, he was posted in Lingmithang to oversee the training of a military force drawn from Kurtoe, Bumthang, Mongar, and Shumar (now Pema Gatshel). He was promoted to the rank of Maktsi wogma [Lieutenant Colonel] on 7 August 1962, and served as the Commandant of the Training Center from 1963 to 1964. On 25 November 1964, he was appointed as the Chief Operations Officer at the army headquarters in Thimphu by the King Jigme Dorji Wangchuck, who promoted him to Maktsi (Full Colonel) in 1970, and promoted him to the rank of Goongloen Wogma (Major General) in June 1981. He was further promoted as Goongloen Gongma (Lt. General) on August 2, 1991.