Having been appointed to the civil service of the British East India Company, of which one of his uncles was a director, he arrived at Calcutta (now Kolkata) early in 1796 where he filled several subordinate posts.

In 1801 he was transferred to the Diplomatic Service where he was posted as the assistant to the British resident Josiah Webbe at the court of the Peshwa ruler Baji Rao II.

In the Peshwa court he obtained his first opportunity of distinction, being attached in the capacity of diplomatist to the mission of Sir Arthur Wellesley to the Marathas.

In 1808 he was appointed the first British envoy to the court of Kabul, Afghanistan, with the object of securing a friendly alliance with the Afghans against Napoleon's planned advance on India.

The most valuable permanent result of the embassy was in Elphinstone's work titled Account of the Kingdom of Cabul and its Dependencies in Persia and India (1815).

[3] After spending about a year in Calcutta arranging the report of his mission, Elphinstone was appointed in 1811 to the important and difficult post of resident at Pune.

Elphinstone assumed command of the military during an important crisis during the Battle of Khadki also called Third Anglo-Maratha War and managed to secure a victory[3] despite his non-military background.

[4] His connection with the Bombay Presidency is commemorated in the endowment of Elphinstone College by local communities, and in the erection of a marble statue by the European inhabitants.

[7] Returning to Britain in 1829, after an interval of two years' travel, Elphinstone continued to influence public affairs,[3] but based in England rather than Scotland.