Crewes, participant in Bacon's Rebellion, was born in England and was the brother of Edward Crewes and Francis Crewes, residents of London. The place or places of their births and names of their parents are not known. James Crewes consistently signed his name in that fashion, but contemporaries sometimes spelled the surname without the second e. While in London on December 1, 1652, Crewes signed a deposition concerning the death of an acquaintance in Virginia the previous year. At that time Crewes described himself as a twenty-nine-year-old merchant. Little else is known about his life in England other than that he was educated; he later owned a Latin Bible, which suggests he knew that language.

The 1652 deposition indicates that Crewes had been in Virginia in 1651, and the appearance of his name on headright lists suggests that in his capacity as a merchant he may have made four or more trips to Virginia. Like many other merchants, he eventually settled in the colony, certainly not later than 1655. He acquired 541 acres of land on Turkey Island in Henrico County. The house that he owned there twenty years later was substantial, with four fireplaces, brick chimneys, and a separate kitchen. As part of his continued commercial interests, Crewes also kept a store, engaged in the fur trade, and dealt with business associates back in England. By 1670 he was a captain of militia.

Charles City County Court records beginning in December 1655 contain references to Crewes acting as a merchant, witness, jury member, trustee, and executor of estates. During the winter of 1655–1656 one of the disputes in which he was involved led to blows and a stabbing that was not fatal. Crewes acquired a few servants, including two or more of African descent, and he obtained permission to keep an Indian servant. He probably married Margaret Llewellin, who witnessed a will as Margaret Crewes on May 1, 1662, but when Crewes wrote his own will in 1676, he had no living wife or children. He bequeathed property to relatives of Giles Carter, but whether he was related to Carter by marriage or otherwise is not certain.

During the winter of 1675–1676, Crewes, William Byrd I, and a few other residents of Henrico County persuaded their near neighbor Nathaniel Bacon to take the lead in organizing local men to defend the colony against anticipated Indian attacks. In the spring, after Bacon had attacked and defeated some Indians and Governor Sir William Berkeley had rebuked him and removed him from his seat on the Council, Crewes and Bacon won election to the House of Burgesses from Henrico County. On May 26, 1676, a week before the General Assembly met, Crewes told Berkeley that Bacon wished to appeal to the Crown the governor's condemnations of his actions. When the assembly met, Bacon made repeated demands that he be commissioned a general to wage war on the Indians, and the colony then erupted into civil war. Crewes took the side of Bacon against the governor. In Berkeley's colorful phrase, Crewes acted throughout as "Bacons Parasite, and Trumpett that continually went about the Country extollinge all Bacons actions & Justifyinge the Rebellion."

The actions of Crewes are poorly documented, but he took the precaution of writing his will on July 23. Eleven days later, on August 3, 1676, when Bacon issued one of his proclamations at Middle Plantation, Crewes signed the document. He was probably one of the men who circulated copies for subscription and perhaps carried along his small English-language Bible to administer oaths of allegiance. It is possible that he marched with a company of Bacon's men as far southeast as Lower Norfolk County during the autumn. Crewes may have been one of the last of Bacon's principal followers to be captured. He was almost certainly among the fifteen or sixteen men the captain of the warship Young Prince delivered to the governor on January 19, 1677.

Berkeley presided at a court-martial at Green Spring, in James City County, on January 24, 1677, at which Crewes and six other men were tried and convicted of treason and rebellion against the king. The trial record singled out Crewes as "a most notorious Actor & Assistor in the Rebellion." James Crewes was sentenced to be hanged at Jamestown on the following Friday, January 26, 1677. The place of his burial is not recorded. The property of the condemned men was subject to confiscation, but the king declined to proceed against Crewes's estate. In August 1684 William Randolph purchased a portion of the Turkey Island property, which became the seat of the subsequently influential Randolph family of Virginia.