Broadfoot was the eldest of four brothers (three of whom died in military service), and entered the Indian army as an Ensign in the 34th Regiment of Madras native infantry, in January 1826. The greater part of his early service was passed with this regiment. Returning to England on furlough in 1836, he held the appointment of orderly officer at Addiscombe Military Seminary for thirteen months. In May 1841 he was sent to Kabul in command of the escort which accompanied the families of the Afghan chiefs, Shah Sujah and Zemán Shah to that place. On reaching Kabul, part of the escort was formed into a company of sappers and miners, which, under the command of Broadfoot, marched with Sir Robert Sale's force from Kabul to Jalalabad in October 1841, Broadfoot being specially mentioned in the despatches for his gallantry in the actions with the Afghans between Kabul and Gandamak. At Jalalabad Broadfoot became garrison engineer, and by his skill and vigour speedily restored the defences of the town, which had been found in a ruinous condition. Having no men from the Sappers and Miners available, he used Gurkha troops as an ad hoc engineer workforce.
During the siege of Jalalabad by the Afghans, Broadfoot (now a Captain), aided by his friend Henry Havelock, then a Captain of foot, was instrumental in preventing a capitulation, which at one time had been resolved on by Sir Robert Sale and a majority of the principal officers of the force. In one of the sorties made by the beleaguered garrison Broadfoot was severely wounded. He subsequently accompanied General Pollock's army of retribution to Kabul, again distinguishing himself in the actions which were fought at Mammu Khél, Jagdallak, and Tezín. At the close of the war he was created a Companion of the Order of the Bath, and was appointed Commissioner of Moulmein, from which office he was transferred to that of agent to the governor-general on the Sikh frontier.
While filling the latter post Broadfoot was present at the sanguinary engagements of Mudki and Ferozshah, in the last of which (21 December 1845) he was mortally wounded. His death and his services were thus described in Sir Henry Hardinge's report on the battle:
It is now with great pain that I have to record the irreparable loss I have sustained, and more especially the East India Company's service, in the death of Major Broadfoot of the Madras army, my political agent. He was thrown from his horse by a shot, and I failed in prevailing upon him to leave the field. He remounted, and shortly afterwards received a mortal wound. He was brave as he was able in every branch of the political and military service.