He was the third son of Mohammad Afzal Khan, and grandson of Dost Mohammad Khan. Abdur Rahman Khan re-established the writ of the Afghan government after the disarray that followed the second Anglo-Afghan war.
He became known as The Iron Amir because his government was a military despotism resting upon a well-appointed army administered through officials absolutely subservient to an inflexible will and controlled by a widespread system of espionage; and for his crushing of a number of rebellions by various tribes who were led by his relatives one of which resulted in the killing and displacement of 60% of the Hazara people's population.
Before his death in Herat, on June 9, 1863, Abdur Rahman's grandfather, Dost Mohammad Khan, nominated his third son, Sher Ali Khan, as his successor, passing over the two elder brothers, Afzal Khan and Azam Khan. At first, the new Amir was quietly recognized. But after a few months, Afzal Khan raised an insurrection in the north of the country, where he had been governing when his father died. This began a fierce internecine conflict for power between Dost Mohammad's sons, which lasted for nearly five years. The Musahiban are descendants of Dost Mohammad Khan's older brother, Sultan Mohammad Khan.
Described by the American scholar and explorer Eugene Schuyler as "a tall well-built man, with a large head, and a marked Afghan, almost Jewish, face", Abdur Rahman distinguished himself for his ability and energetic daring. Although his father, Afzal Khan came to terms with the Amir Sher Ali, Abdur's behaviour in the northern province soon excited the Amir's suspicion and, when he was summoned to Kabul, fled across the Oxus into Bukhara. Sher Ali threw Afzal Khan into prison, and a revolt followed in southern Afghanistan.
The Amir had scarcely suppressed it by winning a desperate battle when Abdur Rahman's reappearance in the north was a signal for a mutiny by troops stationed in those parts and a gathering of armed bands to his standard. After some delay and desultory fighting, he and his uncle, Azam Khan, occupied Kabul in March 1866. The Amir Sher Ali marched up against them from Kandahar; but in the battle that ensued at Sheikhabad on May 10, he was deserted by a large body of his troops, and after his signal defeat Abdur Rahman released his father, Afzul Khan, from prison in Ghazni, and installed him upon the throne as Amir of Afghanistan. Notwithstanding the new Amir's incapacity, and some jealousy between the real leaders, Abdur Rahman and his uncle, they again routed Sher Ali's forces, and occupied Kandahar in 1867. When Afzal Khan died at the end of the year, Azam Khan became the new ruler, with Abdur Rahman installed as Governor in the northern province. But towards the end of 1868, Sher Ali's return and a general rising in his favour resulted in Abdur Rahman and Azam Khan's defeat at Tinah Khan on January 3, 1869. Both sought refuge to the east in Central Asia, where Abdur Rahman placed himself under Russian protection at Samarkand. Azam died in Kabul in October 1869.