On his return to England from Padua, Harvey set about building a career. He first needed membership of the College of Physicians, which controlled the practice of internal medicine in London. He accordingly applied to the college in 1603 and in the next year became a licentiate. In 1604, too, he married a girl whose father was well placed to help Harvey in his career. But his father-in-law, after failing to secure Harvey at post at court, died in 1605. But by the time Harvey was a Fellow of the College he had secured enough influence at court to secure (in 1609) the position of physician to St Bartholomew's Hospital. Harvey also pursued his career in the college with vigour, becoming a censor for the first time in 1614 and an elect before he published his first book. Like the rest of the Harveys, William was able, energetic and did not look down his nose at the material rewards of life. This was important, for it was only by having the financial wherewithal and leisure that Harvey could put his research programme into practice.

Another move made by Harvey to further his career was to accept in 1615 the position of Lumleian lecturer in the college. This was a stipendiary position, and it had been intended by Lord Lumley, in setting up the lectureship in 1582, that the lecturer should receive the equivalent of a university stipend. Harvey no doubt welcomed the money and probably too the opportunity of pursuing human anatomy on an Aristotelian–Fabrician model.