Aikman had planned a career in business. His cousins ran a well established import-export business at Leghorn servicing Anglo-Italian trade. The deaths of his elder brother and father made him, as a very young man, laird of his family estate at Cairnie, on the edge of Arbroath. He came under pressure from his mother's family, the Clerks of Penicuik (his uncle was John Clerk of Penicuik), to study for the Bar but became neither lawyer nor merchant. After a decade of artistic study and travel he emerged as the leading Scottish painter of his generation.
Although Aikman did not serve an apprenticeship to Sir John de Medina he learnt the rudiments of his craft from him. After a short stint in Edinburgh he had moved to London by 1704 and continued his own training. He visited Italy, and through contacts of his cousins, went on to Turkey and Greece. The funds for this extended trip were raised through the sale of the family estate and property in New Jersey. Aikman returned to Scotland in 1711, perhaps precipitated by the news of Medina's death whose role he took over as painter to the Scottish aristocracy and gentry. He was perfectly placed to do so as there were very few other portrait painters in Scotland at that time. In addition, Aikman belonged to the society that he painted and his family and friends helped speed the introductions to Scottish patrons and the Scottish community in London. He spent the last decade of his life here painting amongst others the prime minister, Sir Robert Walpole, and various royal sitters. Aikman marked a change - as Medina's knighthood in 1707 had done - in the perception of the place that the art of painting took in society.