As a young man Robert migrated to Canada about the close of the American Revolution and entered the fur trade. In 1787 he was employed as interpreter and storekeeper of government goods at a great Indian council held at Michilimackinac. As a result of this council he began trading operations among the Sioux. Apparently his position and influence were recognized, for in 1803 the governor of Indiana Territory, which included part of Dickson's trading area, appointed him a justice of the peace for St. Clair County.
In 1805 a firm known as Robert Dickson & Company was formed, with headquarters at Michilimackinac. Two years later this firm became a member of the recently organized Michilimackinac Company.
When the War of 1812 broke, Dickson's position became a matter of significance on both sides: the American leaders took steps to prevent him from bringing his Indians to the aid of the British; and Governor Brock of Upper Canada selected him as his agent to keep the Indians of the Northwest friendly and to lead them to Canada to join the British forces. In the capture of Michilimackinac he and his Indians played a significant role and thus aided indirectly, also, in the capture of Detroit.
In January 1813 his services and influence were recognized by a commission from Governor-General Prevost making him agent for the Indians west of Lake Huron, with extensive authority. Later he was made superintendent of Indian affairs for these tribes. His power, however, awoke the jealousy of military men in the Northwest and led to his arrest at the close of the war and to his dismissal from the service in 1815. He claimed and secured from the British government a hearing in London which not only cleared his name but recognized his services to the extent of awarding him the title of lieutenant-colonel and a retirement pension of £300 a year.
At the close of the war Dickson made arrangements with Lord Selkirk to carry on his business within the supposed limits of the latter's colony on the Red River, close to Dickson's former post. A part of his plan seems to have been an agricultural and industrial settlement of Indians and traders on the site of Grand Forks, North Dakota. In the midst of his plans, however, Lord Selkirk died, and shortly thereafter Dickson himself died suddenly at Drummond Island.
About the year 1797 Dickson took as his wife To-to-win, the sister of an influential Sioux chief.