Leverett served as deputy governor under governor Richard Bellingham in 1671–1672, and succeeded to his position after the governor's death. His tenure as governor was chiefly notable because of King Philip's War, and the rising threats to the colonial charter that culminated in its revocation in 1684. The colony angered the king by purchasing the claims of Sir Ferdinando Gorges to portions of Maine in 1677, a territory Charles had intended to acquire for his son, the Duke of Monmouth. Edward Randolph, sent by Charles to report on the New England colonies, reported in 1676 that Leverett believed the colony to be beyond the crown's reach: "He freely declared to me that the "laws made by your Majesty and your Parliament obligeth them in nothing" but what consists with the interest of that colony".