In 1742 Orme went to Calcutta, where his elder brother William was a Writer in the East India Company. Orme engaged himself in the mercantile house of Jackson & Wedderburn at Calcutta, and made a voyage to Surat. On returning to Calcutta in 1743 he was himself appointed a Writer in the East India Company's service. He acquired a reputation for knowledge of Indian customs, and in 1752 was asked to state his opinion on the regulation of the police in Calcutta. In 1753 he visited England, and during his absence in 1754 was appointed by the court of directors a member of the council at Madras. Returning to India, he arrived at Madras on 14 September 1754. He took an active part in the deliberations of the council respecting the military operations in the Carnatic, 1754–8, and recommended the appointment of Clive to command the expedition against Suráj-ud-Dowlah. Orme was for some years close to Clive, but the friendship was broken off about 1769.